Patent Publication Number: US-8989879-B2

Title: System and method for a demand driven lean production control system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/563,348, filed on 23 Sep. 2009 and entitled “System and Method for a Demand Driven Lean Production Control System,” which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/100,713, filed 27 Sep. 2008, entitled “DMK: An Advanced Demand Driven Lean Production Control System.” U.S. patent application Ser. No. 12/563,348 and U.S. Provisional Application Ser. No. 61/100,713 are commonly assigned to the assignee of the present application. The disclosure of related U.S. patent application Ser. No. 12/563,348 and U.S. Provisional Application Ser. No. 61/100,713 are hereby incorporated by reference into the present disclosure as if fully set forth herein. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates generally to production control systems, and more particularly to a system and method for a demand driven lean production control system. 
     BACKGROUND OF THE INVENTION 
     In a traditional lean manufacturing environment, a kanban card system (e.g., a physical card) is used as a means to control the production flow on a manufacturing floor. The kanban card system is typically referred to as a pull signal, because the kanban card is attached to a container of parts which travels around the manufacturing floor. When the container is empty, the empty container and the kanban card arrive back at a production resource to refill the container, as component supplies and manufacturing capacity permit. 
     In an effort to overcome the above-discussed deficiencies, a manufacturing entity is required to hold higher or excessive inventories. However, increasing inventory without a forward looking mechanism is unresponsive to real-time demand. In addition, because the kanban card system is backward looking a manufacturing entity is inherently exposed to constraints and bottlenecks on the manufacturing floor. This inability to provide a forward looking production control mechanism is undesirable. 
     SUMMARY OF THE INVENTION 
     A system providing visualization of a production control framework is disclosed. The system includes a database storing production control data associated with one or more entities and a production control system coupled with the database and configured to model a production control framework of the one or more entities. The production control system includes one or more work centers authorizing one or more tasks for one or more parts and one or more manufacturing processes that produce one or more finished parts using the one or more parts. 
     A method providing visualization of a production control framework is disclosed. The method provides for storing production control data associated with one or more entities in a database. The method further provides for authorizing one or more tasks for one or more parts at one or more work centers and producing one or more finished parts using the one or more parts at one or more manufacturing processes. 
     A computer-readable medium embodied with software enabling visualization of a production control framework is disclosed. The software is configured to store production control data associated with one or more entities in a database. The software is further configured to authorize one or more tasks for one or more parts at one or more work centers and produce one or more finished parts using the one or more parts at one or more manufacturing processes 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates an exemplary supply chain network according to a preferred embodiment; 
         FIG. 2  illustrates the production control system of  FIG. 1 ; 
         FIG. 3  illustrates an exemplary model of production environment of an entity of  FIG. 1 ; 
         FIG. 4  illustrates an operator dashboard interface provided at each work center of  FIG. 3 ; 
         FIG. 5  illustrates an exemplary method for performing a CONWIP assignment workflow; 
         FIG. 6  illustrates an exemplary method for providing production control authorization signals in the production environment of the entity of  FIG. 1 ; and 
         FIG. 7  illustrates an exemplary method for providing production control signals in the production environment of the entity of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the following detailed description of the preferred and alternate embodiments. Those skilled in the art will recognize that the present invention provides many inventive concepts and novel features, that are merely illustrative, and are not to be construed as restrictive. Accordingly, the specific embodiments discussed herein are given by way of example and do not limit the scope of the present invention. 
       FIG. 1  illustrates an exemplary supply chain network  100  according to a preferred embodiment. Supply chain network  100  comprises a production control system  110 , one or more entities  120   a - 120   n , one or more customers  130   a - 130   n , a network  140 , and communication links  142 ,  144   a - 144   n  and  146   a - 146   n . Although a single production control system  110 , one or more entities  120   a - 120   n , and one or more customers  130   a - 130   n , are shown and described, embodiments contemplate any number of production control systems  110 , any number of entities  120   a - 120   n  and/or any number of customers  130   a - 130   n , according to particular needs. In addition, or as an alternative, one or more other entities  120   a - 120   n  may be, for example, manufacturing entities, manufacturing processes, production facilities, and other like entities. In addition, production control system  110  may be integral to or separate from the hardware and/or software of any one of one or more entities  120   a - 120   n.    
     In one embodiment, supply chain network  100  models a production control technique for, items, products, parts, materials, goods, and/or services through one or more entities  120   a - 120   n  based on demand received from one or more other entities  120   a - 120   n  and/or one or more customers  130   a - 130   n . As described below in more detail, production control system  110  utilizes three types of production control authorizations: DTag production control signals, MTag production control signals and kanban production control signals (i.e., authorizing pull-based production of a standard pack (i.e., incremental (smallest) production quantity of an item). In one embodiment, a DTag production control signal is a demand authorization introduced into production control system  110  via a BOM explosion for all produced parts required to satisfy a demand whenever that demand is introduced into the production control system  110 . For example, the demand may come from a pacemaker operation, and/or, for items that are not scheduled on pacemaker operations, directly from either one or more customers  130   a - 130   n  or an increase of one or more finished good target inventories. 
     In another embodiment, an MTag production control signal is either work center-specific or non-work center-specific (a work center set of one or more production resources, indistinguishable and acting as one for planning purposes). The number of work center-specific MTags, defined at a work center-pair level and specifying both a consuming work center and a producing work center, represents the maximum amount of inventory present at a destination work center which was produced at a particular source (producing) work center. In addition, the non-work center-specific MTags are required for production of any part consuming raw material. In an embodiment, the number of MTags and kanban present in production control system  110  may be fixed at a predetermined level to achieve optimal product flow and inventory levels within one or more entities  120   a - 120   n . In addition, the number of MTags and kanban for each part represents the maximum amount of inventory present in the system for that particular part at a specific time period. 
     In one embodiment, supply chain network  100  may operate on one or more computers that may be integral to, or separate from, the hardware and/or software that support production control system  110 , one or more entities  120   a - 120   n , and one or more customers  130   a - 130   n . These one or more computers may include any suitable input device, such as a keypad, mouse, touch screen, microphone, or other device to input information. In addition, these one or more computers may include any suitable output device that may convey information associated with the operation of supply chain network  100 , including digital or analog data, visual information, or audio information. Furthermore, these one or more computers may include fixed or removable computer-readable storage media, such as magnetic computer disks, CD-ROM, or other suitable media to receive output from and provide input to supply chain network  100 . In addition, these one or more computers may include one or more processors and associated memory to execute instructions and manipulate information according to the operation of supply chain network  100 . 
     In addition, or as an alternative, production control system  110 , one or more entities  120   a - 120   n , and/or one or more customers  130   a - 130   n  may each operate on one or more separate computers or may operate on one or more shared computers. Each of these one or more computers may be a work station, personal computer (PC), network computer, personal digital assistant (PDA), wireless data port, or any other suitable computing device. In another embodiment, one or more users may be associated with one or more entities  120   a - 120   n  and/or one or more customers  130   a - 130   n . These one or more users may include, for example, “planners,” “operators,” and/or “plant managers” handling production control systems, requirements, procedures and policies within supply chain network  100 . In addition, or as an alternative, these one or more users may include, for example, one or more computers programmed to autonomously handle production control systems, requirements, procedures and policies within supply chain network  100 . 
     In one embodiment, production control system  110  may be coupled with network  140  using communications link  142 , which may be any wireline, wireless, or other link suitable to support data communications between production control system  110  and network  140  during operation of supply chain network  100 . One or more entities  120   a - 120   n  may be coupled with network  140  using communications link  144   a - 144   n , which may be any wireline, wireless, or other link suitable to support data communications between one or more entities  120   a - 120   n  and network  140  during operation of supply chain network  100 . One or more customers  130   a - 130   n  may be coupled with network  140  using communications links  146   a - 146   n , which may be any wireline, wireless, or other link suitable to support data communications between one or more customers  130   a - 130   n  and network  140  during operation of supply chain network  100 . 
     Although communication links  142 ,  144   a - 144   n  and  146   a - 146   n  are shown as generally coupling production control system  110 , one or more entities  120   a - 120   n , and one or more customers  130   a - 130   n  to network  140 , production control system  110 , one or more entities  120   a - 120   n , and one or more customers  130   a - 130   n  may communicate directly with each other, according to particular needs. In addition, or as an alternative, production control system  110  may reside within one or more entities  120   a - 120   n  and/or one or more customers  130   a - 130   n , according to particular needs. 
     In another embodiment, network  140  may include the Internet and any appropriate local area networks (LANs), metropolitan area networks (MANS), or wide area networks (WANs) coupling production control system  110 , one or more entities  120   a - 120   n , and one or more customers  130   a - 130   n . Those skilled in the art will recognize that the complete structure and operation of communication network  140  and other components within supply chain network  100  are not depicted or described. Embodiments may be employed in conjunction with known communications networks and other components. 
       FIG. 2  illustrates production control system  110  of  FIG. 1  in greater detail in accordance with the preferred embodiment. As discussed above, production control system  110  comprises one or more computers at one or more locations including associated input devices, output devices, computer-readable storage media, processors, memory, or other components for receiving, processing, storing, and communicating information according to the operation of supply chain network  100 . In one embodiment, production control system  110  stores production control data associated with one or more entities  120   a - 120   n  and/or one or more customers  130   a - 130   n , in database  220 . 
     Server  210  comprises one or more engines  212 , including a demand propagation engine. In addition, although server  210  is shown and described as comprising one or more engines  212 , embodiments contemplate any suitable engine or combination of engines, according to particular needs. Database  220  comprises one or more databases or other data storage arrangements at one or more locations, local to, or remote from, server  210 . Database  220  includes, for example, one or more data modules  222 . As an example only and not by way of limitation, production control system  110  stores production control data associated with one or more entities  120   a - 120   n  and one or more customers  130   a - 130   n  that may be used by server  210 , and in particular, by one or more engines  212 . 
       FIG. 3  illustrates an exemplary model of production environment of entity  120   a  of  FIG. 1  in greater detail in accordance with the preferred embodiment. Entity  120   a  comprises a plurality of work centers  310   a - 310   n  and a plurality of manufacturing processes  320   a - 320   n  that produce one or more finished parts P N . Entity  120   a  further comprises a plurality of production control variables, such as, for example, output buffer of stage i (B i ), demand queuing stage i (D i ), number of DTags in stage i (d i ), unique number identifying a production stage (i,j), kanban queuing station in stage i (K i ), number of kanban in stage i (k i ), MTag queuing station in stage i (M i ), MTag for producer i and consumer j ( 1 m N =CONstant WIP) ( i m j ), manufacturing process of stage i (MP i ), number of manufacturing stages (N), raw material buffer  0  feeding stage  1  (P 0 ), Max inventory of Bi (s i ), synchronization station at stage i (U i ). Although a plurality of work centers  310   a - 310   n , a plurality of manufacturing processes  320   a - 320   n , and a plurality of production control variables are shown and described, embodiments contemplate any number of work centers  310   a - 310   n , any number of manufacturing processes  320   a - 320   n  and/or any number of production control variables, according to particular needs. 
     In one embodiment, each work center  310   a - 310   n  consumes part P i−1  and produces part P i  wherein work center  310   a  is stage  1  and consumes raw material P 0  with, for example, infinite supply. In another embodiment, each buffer B i  has a target inventory of s i  which is set to the sum of capacity buffer and production lead time buffer requirements, which “primes” the value stream with a buffer of high volume parts to improve, for example, system responsiveness. 
     As an example only, and not by way of limitation, whenever a new demand is received at entity  120   a  of  FIG. 1  a demand kanban is generated by exploding the BOM for the demanded part and providing a demand kanban for each additional standard pack required of a component or finished good (i.e., a produced part that is shippable to one or more customers  130   a - 130   n ) part. When a demand kanban appears at a work center it is available to authorize replenishment production of the item, which begins when an empty kanban, as well as empty MTag or CMTag, if needed, is also present and Work Center capacity permits. 
     In addition, the DTag production control signal provides the functionality of extended kanban, which is a production control policy that results in fewer full kanban (less inventory) on average in the system than the standard kanban enables, since standard kanban authorize replenishment as soon as empty kanban arrive at the producing Work Center. The quantity of inventory required by extended kanban on average is less than that required without extended kanban by the quantity of inventory of the part represented by the sum of the number of kanban in the loop size in excess of that required by the current demand signal. Therefore the DTag production control signal provides for controlling excess production in environments where the demand volume and/or mix is variable. 
     In another embodiment, the MTag production control signal is a material authorization signal which provides the functionality of both Paired-cell Overlapping Loops of Cards with Authorizations (POLCA) production control policy and CONstant Work-In-Process (CONWIP) production control policy. POLCA enables management of capacity constrained work centers. For example, POLCA production control techniques constrain replenishment until a POLCA signal is available, which represents available capacity on a downstream work center. The POLCA signals are thus work center-specific, not part-specific, and specify a consuming (generally bottleneck) work center and a producing work center supplying parts to the consuming work center. When the consuming work center is ready to accept more work, which is generally as parts produced at the consuming work center are released to finished good or downstream processes, POLCA signals are released to each producing work center for each standard pack of component parts required. When a POLCA signal appears at the producing work center it is available to authorize replenishment production of component items produced at that work center. In the present invention the MTag signal acts just like the POLCA signal. When MTags are used in conjunction with kanban, replenishment begins when sufficient empty kanban, MTags, and any other required production control signals (such as DTags and/or CMTags) are also present at the producing work center and work center capacity permits. This production control policy results in more empty kanban (less inventory) for the component part on average in the production control system. The MTag, as in POLCA, thus provides for limiting excess inventory in front of, for example, a bottleneck work center. 
     As discussed above, the other production control policy enabled by the present invention is CONWIP, which is enabled by a special form of the MTag, the CMTag. The CONWIP production control policy is similar to POLCA in that it provides a constraint that is not part-specific. The CONWIP authorization signal, the CMTag in the present invention, is neither part-specific nor work center-specific; it is instead site specific. The purpose of the CMTag is to limit the total amount of WIP throughout the production control system (hence the name CONstant WIP). The CMTag provides an additional constraint on production at one or more stage  1  work centers, which work centers generally consume only raw or procured materials. The stage  1  work centers are generally the most upstream work centers in the value stream (supply chain network), and which produce components required in most or all finished good items produced at the site. At such a stage  1  work center, a CMTag is needed for every part produced at that work center, so production may only begin when the number of CMTags available at the work center is the standard pack quantity times the trigger quantity. Once a standard pack is completed, a CMTag is assigned to each unit of material in the standard pack. Each CMTag travels with its assigned component throughout the value stream and is only released back to stage  1  work centers to authorize further production when the finished good comprising the unit of material to which the CMTag is assigned is shipped to one or more customers  130   a - 130   n . At that time the CMTag is released and made available to another initial production work center as appropriate. 
     In one embodiment, if the number of units of stage  1  parts per intermediate or finished good item is large, the number of CMTags in the system may become quite large, and may be bulky or awkward when, for example, physical cards are used to implement CONWIP controls. To mitigate this problem, embodiments provide for selecting a subset of the parts produced at stage  1  work centers for CMTag authorization, rather than all stage  1  produced parts, may be sufficient. If there is a single stage  1  produced part that appears in all finished good items in a relatively constant proportion per finished good item, then enabling CMTag authorization for that one part has much the same effect on the system as enabling CMTag authorization for all stage  1  parts. However, if the distribution of this part is such that there are more units of the part in some finished good items than others, then enabling CMTag authorization for only this part will allow more finished goods inventory of items that consume less of the part, and less finished goods inventory of those items that consume more of the part. If this is inappropriate, than a subset of parts can be identified that behave in the desired manner, that is, when considered as a group the proportion consumed by each finished good item is approximately the same. When this is the case, CMTag authorization is enabled for that subset of parts, rather than for all stage  1  parts, to achieve the desired CONWIP result. In any case, selecting a subset of parts rather than all stage  1  produced parts implies that production at other stage  1  work centers, not controlled by CONWIP, will not be constrained and therefore excessive inventories may result. 
     In one embodiment, the behavior of CONWIP is such that it only constrains the initial operations of a value stream. That is, since a CMTag is assigned to every single unit of material for key produced parts, there will always be CMTags available for every task at downstream operations, so these operations will not be constrained by CMTags. In addition, the CMTag loop size limits the total amount of inventory possible in the production control system at any particular time, and when enabled in conjunction with kanban, CMTags result in fewer full kanban on average. This is particularly useful in high mix environments where the demand pattern may shift so frequently that keeping the kanban loop sizes fully aligned with the demand mix is impractical. If, for example, the total volume of demand is relatively stable then a constant CMTag loop size can be used in addition to kanban to allow the mix to change with demand and utilize larger kanban loop sizes without incurring the additional inventory expense necessary to maintain responsiveness. Otherwise, when the total volume of demand is relatively unstable, the CMTag loop size must be constantly realigned with the demand signal in order to maintain customer service and optimal inventory levels. In addition, setting the CMTag loop size to the sum of all of the kanban loop sizes in the system disables the CMTag constraint by making it non-constraining. 
     In another embodiment, the kanban production control signal supports pull-based production control on the “production floor” of one or more entities  120   a - 120   n . A kanban is a part-specific signal required to authorize production of a standard pack of that part. The number of kanban signals present in the production control system represents the total amount of inventory of the part possible in the system at any one time. 
       FIG. 4  illustrates an operator dashboard interface  400  provided at each work center  310   a - 310   n  of  FIG. 3 . In one embodiment, operator dashboard interface  400  comprises one or more graphical elements including job queue  410 , production history  412 , and buttons  430 . Although, operator dashboard interface  400  is shown and described as having one or more graphical elements including a visual representation of job queue  410 , a plurality of tasks  411 , production history  412 , production control signal types  420   a - d , and buttons  430 , embodiments contemplate any suitable number of graphical elements, according to particular needs. As will be explained below in greater detail, operator dashboard interface  400  provides a visual representation of a production control framework to, for example, determine which tasks  411  to produce, the order in which to produce tasks  411  and a record of when each task  411  is started and completed for each work center  310   a - 310   n.    
     As discussed above, production control system  110  of  FIG. 2  utilizes three types of production control authorizations, the DTag production control signal, the MTag production control signal and the kanban production control signal, in order to authorize production of one or more tasks  411 . In one embodiment, the DTag production control signal is a part-demand-specific signal, which is derived from level plans published on all pacemakers, including any additional finished good demand that is not supplied at some point by a pacemaker. The consolidated demand production control signal (of pacemaker and extra finished good demand) is propagated to an upstream work center by one or more engines  212 . In addition, or as an alternative, one or more engines  212  explodes a BOM of each demanded part to determine component requirements at each level of the BOM. The requirement being, for example, the component part ID, quantity needed, and a start date which is offset from the pacemaker start time or demand due date by a conservative estimate of the time needed to produce the component part and transport it to the demand source (pacemaker group or finished goods inventory) by the start time/due date. In addition, one or more engines  212  calculates the component requirements and consolidates the unfulfilled requirements into component part standard pack, assigns a due date from the earliest start/due date of any demand represented in each standard pack, and allocates all started and/or full kanban of demanded components to the above demanded standard pack based on, for example, highest priority, while accounting for phase-in/phase-out requirements, other engineering changes, and the like. 
     In one embodiment, the DTag capability is turned on and off at the part level, along with other part-specific data, for example, via a Boolean flag indicating whether a part utilizes the DTag functionality. In one embodiment, the default setting is N. In addition, when the DTag setting is at the part level, once the netted standard pack requirements are determined by one or more engines  212 , a DTag comprising the component part ID and due date is generated for each standard pack requirement for that part. In one embodiment, the DTags are visually represented in the operator dashboard interface  400  for the producing work center. When, for example, more than one work center produces a part, allocation of demand to the relevant work center is defined in a part-work center data table in a demand_proportion field, which must, for example, sum to 1 across all part-work center combinations of each part. 
     In another embodiment, production control system  110  provides a site-wide Boolean flag, print_dtags, to allow DTag signals to be printed into physical cards. If the setting is N, then the DTag printing capability is disabled. However, if the setting is Y than the DTag printing capability is enabled and a DTag printing button is visually displayed in a production control system Master DB (a separate interactive user interface in production control system  110  which provides an overview of the status of the entire production system) wherein the DTag printing button is visually grayed out if all DTags have been printed, otherwise it is visually highlighted to indicate that a DTag printing workflow needs to be completed. In one embodiment, the DTag printing workflow is invoked when a new demand signal is received from one or more customers  130   a - 130   n , for one or more parts requiring DTags. In addition, the dates for the DTags signals are maintained in a current and accurate state by production control system  110  and displayed in the operator dashboard interface  400 . 
     In an embodiment, when the DTag setting is set to N for a part, at the instant a standard pack is consumed and an empty kanban is released (to be returned to the producing work center), production control system  110  provides an empty kanban signal to authorize replenishment production of the part at the producing work center. In addition, if a DTag is not required for that part type then production control system  110  displays a task in operator dashboard interface  400  of the part&#39;s producing work center corresponding to the empty kanban irrespective of any demand in the system for that part. 
     In another embodiment, when the DTag setting is set to Y for a part, new tasks  411  for the part appear in operator dashboard interface  400  based on standard pack requirements for the part from one or more engines  212  rather than, for example, downstream consumption of the part generating empty kanban. When, for example, the DTag setting is set to Y for a part, a separate column in job queue  410  indicates the number of DTags needed for its tasks since tasks will not show up in job queue  410  without a DTag to generate them. In addition, if an unsatisfied DTag exists for a part, a new task  411  is created in operator dashboard interface  400  for that part irrespective of the presence or absence of an empty kanban for that part, and the task  411  is associated with the DTag until the task  411  is started, at which time the DTag is dropped from the production control system  110 . 
     As an example only and not by way of limitation, production control system  110  creates a DTag signal for each standard pack demanded. The DTag is assigned to that standard pack, wherein the DTag is not defined at the work center trigger quantity for the part but at the standard pack level. That is, each task  411  on a work center  310   a - 310   n  is available to satisfy the number of DTags in the trigger (TRG) field  415 , which is the number of standard packs in the trigger quantity. A new task  411  for the trigger quantity of the part on the work center  310   a - 310   n  is created in the operator dashboard interface  400  whenever there are unsatisfied DTags for the part, when other tasks  411  are fully allocated to other DTags. 
     In addition, or as an alternative, when a task  411  is generated to accommodate an unsatisfied DTag, the DTag is assigned to this task  411  and the quantity required by the DTag is assigned to the DTag from the task  411 . In addition, production control system  110  assigns the balance on hand (BOH) field  414  and assigns the days of cover (DOC) field  419  to each task  411  of job queue  410 . The part type and due date from the DTag help define the priority of the task  411 . Any remaining quantity from the task  411  after satisfying current DTags is available to satisfy new DTags for the part, that is, as new DTags are created by one or more engines  212 . In addition, downstream consumption of the part provides empty kanban necessary to authorize tasks  411 , but tasks  411  will always be present in the operator dashboard interface  400  sufficient to satisfy all demand for the part generated by the one or more engines  212  that cannot be satisfied from full kanban (compete standard packs in inventory), wherein an empty kanban signal is not required for the appearance of such tasks in operator dashboard interface  400 . 
     In one embodiment, the kanban (KB) field  420   b  in operator dashboard interface  400  indicates whether the required kanban are also present to complete the authorization. Production control system  110  does not allow the initiation of production of tasks  411  that require more kanban than there are empty kanban for that part in the empty kanban queue at the work center  310   a - 310   n . For example, in order to start production of such tasks  411  the trigger quantity of the task  411  must be decreased to reduce required authorizations until available kanban are sufficient. The task  411  start date calculated by one or more engines  212  is used in the prioritization of the tasks, along with demand type (build-to-order (BTO) or make-to-stock (MTS)) and setup requirements, so that, for example, more urgent tasks are noted and completed first. In addition, once a standard pack requiring a DTag is partly consumed by a downstream process, at the point where its kanban is considered “empty” and released to the upstream producing work center  310   a - 310   n  to authorize further production, the DTag for this standard pack is also removed or deleted from production control system  110 . This embodiment tends on average to slightly overestimate the demand for DTags by the quantity of parts in partial kanban and in started but incomplete standard packs of parent parts consuming the component part. 
     In one embodiment, when one or more engines  212  runs, it first deletes all DTags in the system, generates new DTags based on current demand, assigns DTags to any started and/or full kanban and unstarted tasks  411 , creates new tasks  411  for remaining DTags, and then recalculates the priorities of the unstarted tasks  411  in operator dashboard interface  400  of the producing work center  310   a - 310   n  and sorts these unstarted tasks  411  in each work center  310   a - 310   n  accordingly. When, for example, there are not enough DTags to assign to unstarted tasks  411 , for example, when there has been a decrease in demand, one or more engines  212  deletes remaining tasks  411  without any DTags from operator dashboard interface  400 . 
     In one embodiment, the MTag production control signal represents a material authorization. That is, the MTag grants permission to have material (inventory) in the system based on available capacity (i.e., it is not part-specific). Production control system  110  stores two tables, which define the MTag static data separately from the MTag dynamic data, associated with one or more entities  120   a - 120   n  and/or one or more customers  130   a - 130   n , in database  220 . In addition, production control system  110  utilizes these two tables in the production environment to populate MTags in operator dashboard interface  400 . In one embodiment, the first MTag Type table comprises static data including the following fields, as shown below in Table 1. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Field Name 
                 Type 
                 Default 
                 Description 
               
               
                   
               
             
            
               
                 card_name 
                 ID 
                 required 
                 Unique name for the MTag, indicating the relevant 
               
               
                   
                   
                   
                 work center combination 
               
               
                 description 
                 String 
                 null 
                 Description of MTag, detailing the relevant work 
               
               
                   
                   
                   
                 center combination 
               
               
                 consuming_wc 
                 List 
                 required 
                 downstream work center in MTag work center pair 
               
               
                 producing_wc 
                 List 
                 required 
                 upstream work center in MTag work center pair 
               
               
                 start_date 
                 List 
                 Today 
                 First date card is active. List of dates includes today 
               
               
                   
                   
                   
                 from production control system Site Parameter table 
               
               
                   
                   
                   
                 and any week_start_day (Generally Sunday or 
               
               
                   
                   
                   
                 Monday, populated in the production control system 
               
               
                   
                   
                   
                 Site Parameter table). 
               
               
                 end_date 
                 List 
                 INF 
                 First date card is inactive. List of dates includes INF 
               
               
                   
                   
                   
                 and any week_start_day (Generally Sunday or 
               
               
                   
                   
                   
                 Monday, populated in the production control system 
               
               
                   
                   
                   
                 Site Parameter table). 
               
               
                   
               
            
           
         
       
     
     As shown above, table 1 requires one or more entries (rows) for each MTag. Each entry defines the consuming work center in consuming_wc and the producing work center in producing_wc, wherein each is populated from a list of work centers. The description field may be optionally populated and has “producing_wc to consuming_wc” as its default. The start_date and end_date fields may be populated with defaults that enable the MTag definition indefinitely, but may also be populated with any date defining a weekly boundary (the day of the week, for example Sunday, defined by the parameter week_start_day in production control system Site Parameter table), if desired to enable the MTag only for a particular period. 
     In another embodiment, the second MTag table (Table 2) is the MTag Size table, defining the loop size for each MTag specified in the MTag table, as well as the loop size of the CMTag, (the site-wide CONWIP MTag). CMTag is a special MTag with neither a consuming nor a producing work center defined, and which may always be defined in production control system  110 . The MTag Size table (Table 2) comprises dynamic loop size data including the following fields for each MTag in the MTag table, as well as for the site-wide CMTag, as shown below in Table 2. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Field Name 
                 Type 
                 Default 
                 Description 
               
               
                   
               
             
            
               
                 card_name 
                 List 
                 N/A 
                 Provided from MTag data (or “CONWIP” for the 
               
               
                   
                   
                   
                 CMTag entry) 
               
               
                 description 
                 FString 
                 N/A 
                 Provided from Description in MTag data (or 
               
               
                   
                   
                   
                 “CONWIP authorization” for the CMTag entry) 
               
               
                 max 
                 FInt 
                 N/A 
                 Maximum MTag value, calculated by production 
               
               
                   
                   
                   
                 control system 110 
               
               
                 use_max 
                 Y/N 
                 Y 
                 Should production control system 110 use the max 
               
               
                   
                   
                   
                 value for the quantity? Y effectively turns off MTag 
               
               
                   
                   
                   
                 capability by making it non-constraining 
               
               
                 quantity 
                 Int &gt; 0 
                 Max 
                 Loop size: the number of cards deployed in system. 
               
               
                   
                   
                   
                 Max is unconstraining, indicating that the MTag is 
               
               
                   
                   
                   
                 ineffective, or turned off. 
               
               
                 start_date 
                 Date 
                 Today 
                 First date quantity of card active. List of dates 
               
               
                   
                   
                   
                 includes start_date from the corresponding MTag 
               
               
                   
                   
                   
                 definition in the MTag table and any following 
               
               
                   
                   
                   
                 week_start_day (Generally Sunday or Monday, 
               
               
                   
                   
                   
                 populated in production control system Site 
               
               
                   
                   
                   
                 Parameter table) before the end_date. 
               
               
                 end_date 
                 Date 
                 INF 
                 Last date quantity of card active. Cannot be on or 
               
               
                   
                   
                   
                 before the start_date above or after the end_date of 
               
               
                   
                   
                   
                 the corresponding MTag definition in the MTag 
               
               
                   
                   
                   
                 table. 
               
               
                   
               
            
           
         
       
     
     In the above Table 2, use_max, quantity, and the start_date and end_date fields may be populated by the user of production control system  110 . The use_max field indicates whether production control system  110  should use the value in the max field in the quantity field. In one embodiment, the default for use_max is Y, which disables the MTag feature by making it non-constraining. In this case, any value in the quantity field is ignored. When MTags are enabled in production control system  110  then the use_max field is set to N and a value less than max is entered in the quantity field, which may be a custom value. In addition, the max field may be populated with a very large value, or with a symbol for infinity, for example, “INF.” 
     In addition, or as an alternative, production control system  110  automatically calculates and displays a meaningful value for max. For example, for MTags (those with a producing_wc and consuming_wc populated) this max value may be the sum of the loop sizes of all of the components supplied from producing_wc to consuming_wc and all of the loop sizes of all of the components produced at consuming_wc. That is, when production control system  110  automatically calculates the max default setting, a reasonable constraining boundary is identified and a comparison as to how constraining to the production control system a custom entry for quantity will be. For example, any quantity less than max may potentially constrain production flow, and the smaller the custom quantity value is in relation to the max value the more likely material flow will be constrained. In one embodiment, if this feature is enabled, an additional enhancement may be provided to support calculating the quantity of MTags in the system as a proportion of the max value by allowing quantity entries &gt;0 and &lt;1, which yield the quantity of MTags in the production control system when multiplied by max. 
     As discussed above, with respect to Tables 1 and 2, there may be multiple entries for each MTag definition in order to allow for a time-phased control of the MTag behavior. However, there must at all times be exactly one MTag entry in each of Tables 1 and 2 that has a start_date of Today (the production control system  110  start date) and one MTag entry having an end_date of INF (for example, corresponding to eternity or to some date beyond the planning horizon). In one embodiment, the MTag Size table (Table 2) is automatically populated with one row for each MTag defined in the MTag Type table, and one additional row to define the CMTag. 
     If, for example, a planner associated with one or more entities  120   a - 120   n  wishes to enter multiple instances of a particular MTag (CMTag) configuration, the planner may change the start_date or end_date of an existing entry to another weekly boundary (that being a date in the planning calendar corresponding to the day of the week stored in week_start_day). In this case, production control system  110  automatically generates a new MTag (CMTag) entry for the remaining period for which there is no definition, populates the start_date and end_date appropriately, populates the use_max value with “N,” and leaves the cursor in the quantity field for the next planner entry. 
     The interactive MTag tables may also allow a planner to modify entries by adjusting the start_date or end_date to another weekly boundary such that the span between these dates is at least one week, in which case production control system  110  may accordingly adjust the start_date or end_date of the period which is overlapped by the change. In addition, the planner may change the start_date of one entry to be the same as the start_date of some earlier period, or may change the end_date of one entry to be the same as the end_date of some later period. In either case, production control system  110  may automatically remove the overlapped entries, and may also advise the user of the pending event prior to executing it and request the approval of the planner to do so, only executing the event if the planner approves the action. The planner may then generate any desired pattern, and any pattern generated by the planner will exactly partition the planning horizon, such that MTag definitions do not overlap or contain gaps. 
     As an example only and not by way of limitation, production control system  110  deploys the MTags via operator dashboard interface  400 . The number and types of MTags assigned to a produced part at a work center  310   a - 310   n  is derived from the MTag definitions in MTag Tables 1 and 2, and from the relevant BOMs. In one embodiment, each MTag represents a standard pack of input parts consumed at consuming_wc. The number of MTags given in the MTag quantity field in the MTag table for each type of MTag may be distributed among numerous states (states  1 - 5 ) for that MTag depending on the status of, for example, a production floor of one or more entities  120   a - 120   n , in the following order:
         1. All tasks  411  that are currently started at consuming_wc but are not yet released to the downstream work center or inventory buffer, where each physical MTag is attached to a standard pack of parts produced at consuming_wc.   2. In the input queue of consuming_wc, where any physical MTags are attached to full or partial standard pack of consumed parts.   3. Finished standard packs at producing_wc, where MTags are attached to standard packs of parts produced at producing_wc and consumed at consumed_wc.   4. Started (and unfinished) tasks  411  at producing_wc, where MTags are attached to standard packs of parts produced at producing_wc and consumed at consumed_wc.   5. MTag queues at producing_wc, where MTags wait to be attached to tasks as tasks are started.       

     In one embodiment, production control system  110  assigns MTags to each produced standard pack at a work center that is listed in the consuming_wc field in the MTag table. When a new standard pack is started at consuming_wc, for each producing_wc/consuming_wc combination, the new standard pack produced at consuming_wc is assigned the MTags that were assigned to the component part standard packs supplied by producing_wc that are consumed by the new standard pack. In one embodiment, these MTag quantities may be fractional, within production control system  110 , depending on the quantity of items in a standard pack of the produced part, the quantity of items in a standard pack of the consumed part, and the quantity of consumed item consumed per unit of produced item in the BOM. 
     In another embodiment, in a physical deployment of the MTags, the physical MTag may be attached to a standard pack of parts produced at consuming_wc that consumes the last component of the consumed part standard pack to which the MTag was previously attached. In such cases when the standard packs are completed at consuming_wc they are released to the downstream work center or inventory buffer in the order in which they were started. Otherwise, the number of MTags present at the consuming_wc may not properly reflect the total quantities of the consumed parts which are present at the consuming_wc. In such cases, a larger number of MTags may be required for adequate production flow at consuming_wc, and the control over the component inventories at consuming_wc may not be as precise. 
     In one embodiment, when production control system  110  identifies that a completed standard pack leaves an MTag consuming_wc, production control system  110  releases the MTags assigned to that standard pack back to, for example, states  2  through  5  above, first to state  2 , then to state  3 , then to state  4 , then to state  5 . If, for example, the production floor of one or more entities  120   a - 120   n  is executing and reporting production and inventory movements correctly, released MTags may only be moved from 1 to 5, since 2 and 3 may already be saturated with MTags. 
     In one embodiment, an MTag filter  418  is visually illustrated as an option in operator dashboard interface  400  and filters out tasks  411  requiring MTags when, for example, there are no MTags available in the MTag Queue. If MTag filter  418  is turned on (visually checked), tasks  411  may only appear in operator dashboard interface  400  if there are, for example, both sufficient kanban and MTags present in the respective queues. In such a state, all tasks  411  appearing in operator dashboard interface  400  are fully authorized by MTag and kanban availability. In such an embodiment, the MTag (MT) field  420   c  and kanban (KB) field  420   b  provide no additional information and therefore need not be visually represented. MTag filter  418  eliminates visual clutter from operator dashboard interface  400  when kanban loop sizes are significantly higher than MTag availability. 
     In addition, once MTags are released at consuming_wc, normally to, for example, state  5  above, which is the MTag Queue of producing_wc, if additional tasks are available in the producing_wc but are not visually displayed since MTag filter  418  is turned on, implying there are empty kanban in the Kanban Queue that have generated such tasks, then production control system  110  visually displays all tasks that are now fully authorizable in their MTag and kanban requirements. MTags by themselves, without corresponding empty kanban, may not generate new tasks  411  since the MTags are not part-specific. 
     In one embodiment, the kanban and MTag signals are not actually assigned to task  411  when the task is created, but the signals remain in their respective queues until production of task  411  is initiated. A task may not be initiated until it is authorized, and a task may not be authorized until there are at least as many kanban for that part in the kanban queue as the trigger quantity, and at least as many MTags in the MTag Queue, having their consuming work centers defined as the consuming_wc in the MTag, as the trigger quantity. Once an authorized task is initiated, the number of empty kanban for the produced part of the task in the kanban queue, and MTags in the MTag Queue having a consuming_wc that consumes the part, are both reduced by the trigger quantity of the started task. If, for example, there are multiple types of MTags in the MTag Queue with different consuming_wc entries that both consume the same item, indicating there are multiple MTag destinations requesting the item from the work center, production control system  110  assigns the MTag type with the largest percentage of its MTags in MTag Queue, presuming that this measure indicates which producing work center supplying MTags is most in need of component parts. 
     In one embodiment, with respect to the CMTag, at least one CONWIP entry must always be present in the MTag Size table (Table 2) with a generic CMTag card_name of, for example, “CONWIP.” The default value for the max field of this CMTag entry may be infinity, or some extremely large number, for example, one trillion. However, production control system  110  may populate this default value with a more meaningful value, which is a more reasonable boundary condition defining when the CONWIP constraint may become effective. 
     In another embodiment, production control system  110  provides an additional CMTag field in a production control system part data, with default=Y. Production control system  110  stores and accesses production control system part data in database  220 , in, for example, a table. By default, production control system  110  turns on CMTags for all stage  1  parts when CMTags become constraining, and thereby may begin to constrain production of all stage  1  parts. If, for example, production control system  110  implements CONWIP on a subset of the stage  1  parts, the CMTag field is set to N in the production control system part data for those stage  1  parts that are not to be constrained by CONWIP. In addition, or as an alternative, the CMTag field may be ignored for all parts that are not produced at stage  1  work center  310   a , as determined by the BOM and Part-work center data. 
     In one embodiment, a reasonable boundary condition for the CMTag max field is the total quantity of all stage  1  produced parts having CMTag=Y in the production control system part data present in the production control system if all of the kanban in the production control system were full. This quantity is the sum of the products of the loop sizes all of the kanban in the system with their respective consumed quantities of the CMTag components anywhere in their BOM structure, determined via an explosion of the relevant BOM structures in the production control system BOM table. If, for example, the CMTag quantity field is set below this max value and use_max=N, then CMTags begin to constrain production. Any quantity values higher than max may effectively disable CMTag behavior when use_max=N, such that production is never constrained by CMTags. When calculated by production control system  110 , this max value is automatically updated by production control system  110  whenever kanban loop sizes or finished good inventory targets are updated, and is, for example, the largest such value at any point between the start_date and end_date for that entry in the MTag Size table (Table 2). 
     In another embodiment, the site-wide CMTag operates differently and is configured differently than the work center-specific MTags. For example, when production control system  110  enables CONWIP (CMTag quantity setting lower than max in current time period and use_max=N), a CMTag is required by production control system  110  to authorize production of a CMTag part (any part having CMTag=Y in part data) at stage  1  work center  310   a  (e.g., a work center consuming only raw or procured materials). In addition, a CMTag is never required by any other type of task (since any other task in production control system  110  will be consuming a component that has at least 1 CMTag assigned to it). When use_max=N during the current time period, any CMTag quantity setting lower than the max value during the current time period causes the operator dashboard interface  400  of every stage  1  work center  310   a  which may produce a stage  1  CMTag part to visually display a CONWIP (CW) field  420   d  and a CONWIP button  434 . 
     In one embodiment, CMTags are deployed at stage  1  work center  310   a  via a CMTag Queue. For each task  411  requiring CMTags in job queue  410  of stage  1  work center  310   a , the CONWIP (CW) field  420   d  displays the number of CMTags needed for authorization of the task in addition to the number of CMTags already present in the CMTag Queue at work center  310   a.    
     In an embodiment, when CMTags are constraining material flow, stage  1  work center  310   a  is often starved of empty CMTags and places a CMTag request to one or more engines  212  that manage the distribution of empty CMTags among the stage  1  work center  310   a  when CMTags are released from finished good inventory (which is when a finished goods standard pack is shipped from the finished goods inventory system). To enable this CONWIP request and acquisition workflow when CMTags are in effect at a stage  1  work center  310   a , an additional field  435  is visually displayed in the operator dashboard interface  400  that indicates the number of CMTags represented in unfulfilled CONWIP requests already made by other Work Centers 
     The value in field  435  provides a visual indication of how long a wait may be until a new CONWIP request is fulfilled. For example, a value of 0 in the CONWIP (CW) field  420   b  means that there are no unfulfilled CONWIP requests in the system, and that selecting the CONWIP button generates a new CONWIP request that would be satisfied by before any other work center&#39;s CONWIP request, such that the work center will receive all CMTags that become available until the new CONWIP request is fulfilled. If, for example, field  435  is highlighted, the value indicates that an open CONWIP request has been made and the visually displayed value is the number of CMTags required to fulfill earlier CONWIP requests made by other work centers, which were made before the current CONWIP request by the current work center. 
     In one embodiment, a check mark in CONWIP (CW) field  420   b  visually indicates that there are sufficient CMTags available in the CMTag Queue of the work center to authorize production of the task. The CMTags in the CMTag Queue are available to authorize any task  411  requiring CMTags for authorization; the CMTags are not assigned to tasks  411  requiring them until tasks  411  are started, and so all CMTags at the work center are available to all unstarted tasks at the work center to authorize whichever task  411  is started. If, for example, the number of CMTags available in the CMTag queue at stage  1  work center  310   a  is insufficient for a particular task  411 , the remaining required quantity of additional CMTags needed to authorize task  411  may be displayed in CONWIP (CW) field  420   b  for that task, and may also be requested by one or more engines  212 . 
     As an example only and not by way of limitation, one or more engines  212  enables automatic distribution of CMTags across stage  1  work center  310   a  based on CMTag requests and task priorities. In doing so, production control system  110  defines a free CMTag as a CMTag that is not assigned to a started (or finished) task or to a work center to satisfy a CONWIP request. Remaining CMTags are assigned, either to stage  1  work center  310   a  or to parts produced at stage  1  work center  310   a . Assigned CMTags become free when finished goods containing the relevant stage  1  produced parts are shipped from one or more entities  120   a - 120   n , in which case the number of CMTags consumed by the finished good item in its order tree are released to the one or more engines  212 . CMTags are also released to one or more engines  212  when the respective work center starts a task that requires fewer CMTags than the quantity assigned to the work center, in which case the remaining CMTags assigned to the work center are released to one or more engines  212 . Each shipped finished good component releases one CMTag for each unit of a CMTag part it comprises. 
     In addition, when the CMTags are activated (CONWIP entry quantity&lt;max and use_max=N in MTag Size table (Table 2) in MTag definition effective in current period). One or more engines  212  perform the CONWIP assignment workflow (discussed in more detail below) on a predetermined time basis, such as, for example, every 30 seconds, 1 minute, or any other predetermined basis. 
     In order to further explain the operation of the CONWIP assignment workflow, an example is now given. In the following example, each work center  310   a - 310   n  producing a CMTag part (even theoretically, based on the BOMs of the parts assigned to the work center for production, even if there is currently no demand for the part) CONWIP button  434  may be present in the particular work center&#39;s operator dashboard interface  400 . CONWIP button  434  may be grayed out unless the selected task in job queue  410  is CMTag infeasible due to lack of CMTag availability at the work center, in which case there are insufficient CMTags available in the CMTag Queue at the work center to authorize the selected task due to insufficient free CMTags in the system. In this case, when the selected task is CMTag-infeasible, the CONWIP button  434  is visually highlighted in the operator dashboard interface  400 . 
     A different task  411  may be selected, such as a task that is CMTag feasible or one that does not require CMTags. In addition, a CONWIP request may be requested which opens a request to one or more engines  212  for the standard pack quantity times the trigger quantity of the selected task. Any other task with sufficient CMTags available or a task that does not need CMTags may then be started, wherein the START button  431  is visually highlighted in order to initiate production. If, however, another task  411  is selected that has insufficient CMTags during an open CONWIP request then CONWIP button  434  is visually highlighted, only if the selected task needs more CMTags than what has already been requested from one or more engines  212 . If CONWIP button  434  is then selected, the earlier unsatisfied CONWIP request is cancelled and a new CONWIP request is submitted to one or more engines  212  for the total quantity needed for the selected task and placed last in the queue of open CONWIP requests in one or more engines  212 . In this manner, the CONWIP assignment workflow only permits one open CONWIP request in one or more engines  212  from any one work center at any one time. 
     In addition, or as an alternative, in fulfilling CONWIP requests, one or more engines  212  assign the requested quantity of CMTags to the work center of the CONWIP request that has been open the longest (a FIFO assignment), or if there isn&#39;t enough to satisfy the request, all remaining CMTags, in which case one or more engines  212  tries to complete this last unfulfilled request first in the subsequent CONWIP assignment workflow. The CONWIP button is grayed out in the operator dashboard interface  400  when one or more engines  212  satisfy the CONWIP request. All CMTags assigned to the work center in fulfillment of a CONWIP request remain assigned to the work center until the next task  411  is started on that work center. A task  411  that is authorizable may be started whenever no task is currently running on the work center. If a task  411  is started requiring CMTags then the CMTags required by that task are assigned to the task from the CMTags available at the work center, and these CMTags remain assigned to the units of material in the standard pack until finished good items fed by the task  411  are shipped from one or more entities  120   a - 120   n . Any remaining CMTags assigned to the work center are then released to one or more engines  212  as free CMTags and are available for redistribution by one or more engines  212  in the next CONWIP assignment workflow. These released CMTags remain in the CMTag Queue of the work center until they are recalled by one or more engines  212 , and while in the CMTag Queue are available to authorize further production at the work center. 
     In another embodiment and to further explain the operation of operator dashboard interface  400 , an example is now given. In the following example, job queue  410  displays a list of all tasks currently planned at each work center  310   a - 310   n  and provides visibility concerning the status of each task  411 . As an example only and not by way of limitation, operator dashboard interface  400  visually displays seven tasks  411  in job queue  410  (although scroll bar  421  indicates the presence of many other lower-priority tasks  411  in the queue, not shown). Although only seven tasks  411  are visually shown in  FIG. 4 , embodiments contemplate (as indicated by the scroll bar  421 ) any number of tasks  411 , according to particular needs. 
     In one embodiment, tasks  411  are sorted by the priority (P) fields  413  such that, for example, the highest priority tasks (i.e., with smaller priority values) appear at the bottom of job queue  410 , near production history  412  (tasks in the bottom portion of operator dashboard interface  400 ). Although a particular priority is shown and described, any suitable sorting or prioritization may be applied to tasks  411 , according to particular needs. 
     In another embodiment, production control signal types  420   a - d  of job queue  410  indicate whether or not each task  411  comprises the appropriate authorizations in order to authorize production. If not, production control signal types  420   a - d  indicate how many additional signals of each relevant production control signal types  420   a - d  are required to authorize the task. For example, tasks  411  having the required authorization production control signals available to authorize production provide a visual indication of a check mark in the respective fields of the particular production control signal types  420   a - d . In addition, tasks  411  that do not have the required authorizations of a particular production control signal type  420   a - d  visually indicate in the respective fields how many additional authorization production control signals of that type each task  411  requires in order to authorize production (i.e., 2, 3, 4, etc.). 
     In an embodiment, trigger (TRG) field  415  displays a trigger value when the required number of kanban for each task  411  in job queue  410  exceeds a predetermined value, such as for example, one. The trigger value is the number of kanban required for each part associated with each task  411  to authorize production. 
     In another embodiment, production control system  110  displays the MTag (MT) field  423  when any MTags exist which have the particular work center  310   a - 310   n  as the producing work center  310   a - 310   n . Any parts produced on the producing work center  310   a - 310   n  and consumed on the consumed work center  310   a - 310   n  of such an MTag will populate the MTag (MT) field  423  on the producing work center  310   a - 310   n . However, if a task  411  does not require a production control signal type  420   a - d  then the MTag (MT) field  423  remains blank for the respective field. In addition, unselected tasks  411  that are ready (i.e., fully authorized for all required production control signal types  420   a - d  other than CONWIP), are visually represented by highlighting in, for example, a different color and/or font type. In addition, the selected task  411  is visually highlighted, in for example, a different color and/or font type, whether it is fully authorized for production or not. Although a particular visual representation of highlighting is described, embodiments contemplate any suitable highlighting in color, text color or style of font of the text, such that the visual representation of the data may be visually highlighted, according to particular needs. 
     In an embodiment, production of a ready task  411  in job queue  410  is initiated with sufficient CMTags, one of the highlighted tasks is selected (if the desired task is not already visually highlighted in a different manner, which is by default the bottom task in the sorted list when no tasks are currently running on the work center  310   a - 310   n ). This action visually grays out START button  431 , moves the selected task  411  into the production history  412  of operator dashboard interface  400  and visually highlights PAUSE button  432  and DONE button  433 . When task  411  is finished, the operator may select the DONE button  433 , or the production control system may automatically select DONE button  433  upon completion of the task, at which time the DONE button  433  may be visually grayed out, which completes the task&#39;s production history  412  information, and the last unstarted task in job queue  410  and START button  431  may then be visually highlighted. As discussed above, although a particular visual highlighting is shown and described, data may be highlighted according to any suitable needs. 
     Modifications, additions or omissions may be made to operator dashboard interface  400  without departing from the scope of the invention. As an example and not by way of limitation, operator dashboard interface  400  may have more, fewer, or other graphical elements. Moreover, the operation of operator dashboard interface  400  may be performed by more, fewer, or other graphical elements, arranged in any suitable manner, according to particular needs. 
       FIG. 5  illustrates an exemplary method  500  for performing a CONWIP assignment workflow. The method begins at step  502 , when the CMTags are activated (CONWIP entry quantity&lt;max and use_max=N in MTag Size table (Table 2) for an MTag definition effective in current period). As discussed above, one or more engines  212  perform the CONWIP assignment workflow on a predetermined time basis. 
     At step  504 , one or more engines  212  determines if there is an open (unsatisfied) CONWIP request from a stage  1  work center  310   a . If there are open (unsatisfied) CONWIP requests, the method proceeds to step  506 , otherwise, the method proceeds to step  510 . 
     At step  506 , one or more engines  212  recalls any free CMTags, in quantities sufficient to satisfy open CONWIP requests, and assigns sufficient free CMTags to each stage  1  work center  310   a  generating a CONWIP request, in, for example, a First-in First-out (FIFO) manner, satisfying older CONWIP requests first. Next at step  508 , one or more engines  212  close satisfied CONWIP requests, that is, close requests where one or more engines  212  has assigned to the requesting work center the requested quantity of CMTags in that work center&#39;s open CONWIP request. 
     At step  510 , one or more engines  212  prioritize all unstarted CMTag tasks  411  planned on any stage  1  work center  310   a  which are authorizable apart from the CMTag (those tasks which have sufficient authorization and inventory otherwise) on a common priority scheme comparable to that used in operator dashboard interface  400  at each stage  1  work center  310   a . Next, at step  512 , one or more engines  212  allocate remaining free CMTags to work centers to satisfy tasks  411  by highest priority, update the relevant values in the CONWIP (CW) field  420   d  of job queue  410 , but do not assign these free CMTags to the work center. (The CMTags are still considered free, and will be recalled from the work center to fulfill open CONWIP requests as needed, first from work centers with the lowest priority tasks. Until such time as free CMTags are recalled by one or more engines  212 , they remain available to authorize any task at that work center.) 
     Next at step  514 , one or more engines  212  determine if any free CMTags remain. If there are any free CMTags, the method proceeds to step  516 , otherwise, the method ends. At step  516 , one or more engines  212  makes the remaining free CMTags available to stage  1  work center  310   a  with the largest sum of the values in the CONWIP (CW) field  420   d  and updates the CONWIP (CW) fields  520   d  values accordingly. Once the CONWIP (CW) fields  520   d  are updated, the method ends. In addition, although,  FIG. 5  illustrates one embodiment of a method for performing a CONWIP assignment workflow, various changes may be made to method  500  without departing from the scope of embodiments of the present invention. 
       FIG. 6  illustrates an exemplary method  600  for providing production control authorization signals in the production environment of entity  120   a . The method begins at step  602 , where a demand signal is received from one or more customers  130   a - 130   n  at production control system  110 . The demand signal is propagated into N+1 DTag signals, 1 for each of N work centers  310   a - 310   n  and 1 for the final finished goods buffer. At step  604 , a distinct DTag is produced for each standard pack of each part ID required at every work center, after rounding up the gross requirement of each part to the nearest standard pack. In addition, dependent component material requirements are propagated to upstream work centers based on, for example, lead times, BOMs, yield and engineering change notice (ECN). 
     In one embodiment, production control system  110  replaces all existing DTags and re-propagates the entire DTag signal each time the demand signal is updated. In another embodiment, production control system  110  provides a net change type of workflow wherein only the new demand signals are propagated. In either embodiment, the DTag is deleted or destroyed once it has succeeded in authorizing production of a standard pack and production has been initiated. In addition or as an alternative, if that standard pack is not completed or is scrapped, other means in the production control system may be initiated to make up the production, as in the use of safety stock, etc, such that the DTag need not be recreated. 
     At step  606 , Synchronization Station U i , shown in  FIG. 3  coordinates the timely aggregation of multiple production authorization signals to ensure that all authorizations required by task  411  are present before production is initiated. Each U i  may have up to 4 production authorizations, a DTag which is satisfied (destroyed) when production begins (d i ), kanban which is a standard production authorization (k i ), an MTag for each MTag having WC i  in producer list and wc, in consumer list ( i m j ), and a CMTag at MP 1  MTag loopsize with null producer/consumer work centers (m). 
     At step  608 , when the first item in a standard pack of a part P i  produced at MP i  is consumed by part P i+1  produced at MP i+1 , the kanban k i  is returned to kanban queuing station K i . At step  610 , MTags  i m j  return to queuing station M i  when part P i+1  is released to MP i+2 . At step  612 , CONWIP MTags m are released only when finished good parts containing them are shipped to one or more customers  130   a - 130   n . Once the CONWIP MTags m are released, the method ends. In addition, although,  FIG. 6  illustrates one embodiment of a method for providing production control authorization signals in a production environment, various changes may be made to method  600  without departing from the scope of embodiments of the present invention. 
       FIG. 7  illustrates an exemplary method  700  for providing production control signals in the production environment of entity  120   a . At step  702 , production control system  110  determines if a part requires a DTag. If a part requires a DTag, the method proceeds to step  704 , otherwise, the method proceeds to step  714 . At step  704 , production control system  110  posts a new task  411  for that part in operator dashboard interface  400  of the producing work center as soon as a DTag for the part is present in the production control system, which cannot be satisfied by the tasks for that part currently created in job queue  410  (since they may be fully assigned to other DTags). At step  706 , production control system  110  creates a task  411 , even if no other signal required for authorization is present (MTag, CMTag and/or kanban). 
     At step  708 , production control system  110  displays an additional field in job queue  410  for each additional production authorization signal required by any task  411  in job queue  410 . At step  710 , production control system  110  determines if any task  411  in work centers  310   a - 310   n  requires an MTag and if MTag filter  418  is off (unchecked). If an MTag is required and MTag filter  418  is off, the method proceeds to step  712 , otherwise, the method proceeds to step  714 . At step  712 , production control system  110  displays the MTag (MT) fields  520   c  and Kanban (KB) fields  520   b  in operator dashboard interface  400 . In addition, if CONWIP is enabled for any part produced at a stage  1  work center  310   a  then the CONWIP (CW) field  420   d  may be displayed in operator dashboard interface  400  of work center  310   a.    
     At step  714 , production control system  110  determines if the part requires a work center-specific MTag. If a part requires a work center-specific MTag, the method proceeds to step  716 , otherwise, the method proceeds to step  722 . At step  716 , production control system  110  determines if MTag filter  418  is off. If MTag filter  418  is off, the method proceeds to step  718 , otherwise, the method proceeds to step  720 . 
     At step  718 , production control system  110  posts a task  411  for that part in operator dashboard interface  400  of the producing work center as soon as an empty kanban appears for that part. At step  720 , production control system  110  visually displays the task only when there are sufficient MTags and kanban available to authorize production of a standard pack the part, which may be less than trigger quantity. 
     At step  722 , production control system  110  visually displays a task  411  for the part in operator dashboard interface  400  of the producing work center as soon as an empty kanban signal is produced at a downstream work center and the execution of all of the tasks for the part currently open on the work center would not consume all of the empty kanban for that part. 
     At step  724 , production control system  110  determines if tasks  411  are considered ready and if all production authorizations required for task  411  except the CMTag are available in their respective queues at the work center. When tasks  411  are considered ready, the method proceeds to step  726 , otherwise, the method continues to determine whether tasks  411  are ready. 
     At step  726 , production control system  110  visually highlights the ready tasks  411 , in for example, alternating lighter and darker shades of highlighting color. In addition, or as an alternative, production control system  110  visually highlights the START button  431  when the task is selected so that the task on the work center can be started if the task: does not require the CMTag, or requires the CMTag and the work center has sufficient CMTag available to authorize the task. In addition, production control system  110  visually highlights the CONWIP (CONWIP) button  434  if they require CMTags and there are insufficient CMTags available in the CMTag Queue of the work center. Otherwise the task remains un-highlighted and the task is not able to be selected. 
     Once ready tasks  411  are selected, the method ends. In addition, although,  FIG. 7  illustrates one embodiment of a method for providing production control signals in the production environment, various changes may be made to method  700  without departing from the scope of embodiments of the present invention. 
     In accordance with the principles of embodiments, the DTag, MTag (and CMTag) and kanban production authorization control signals may be invoked in any of various combinations in order to control production within one or more entities  120   a - 120   n , as needed. As an example only and not by way of limitation, DTags may be utilized in environments where demand is volatile and/or the BOM is complex and/or the amount of time required to produce finished goods from raw materials is significant. Similarly, MTags may be utilized to manage production flow through intermediate capacity constrained work centers to minimize excess inventory and provide for smooth production flow. Similarly, CMTags may be utilized in environments where product mix is volatile and/or the number of component parts used in production is significant. Similarly, kanban may be utilized in environments where production constraints are in the latter stages of production, and/or where production processes and/or component supplies are unreliable and/or in environments where is it impractical to publish a manufacturing plan in an accurate and timely manner. 
     Reference in the foregoing specification to “one embodiment”, “an embodiment”, or “another embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     While the exemplary embodiments have been shown and described, it will be understood that various changes and modifications to the foregoing embodiments may become apparent to those skilled in the art without departing from the spirit and scope of the present invention.