Abstract:
The present invention relates to a cleaning policy and a method for recovering error in a file system using flash memory; and, more particularly, to a ranked cleaning policy in a file system using flash memory which can be used effectively and longer by dividing it into segments, adopting the ranked cleaning policy and arranging cleaned spaces evenly, and to an error recovery method in a file system using flash memory which can recover error by subdividing cleaning status when sudden power error is caused, as well as to a computer-based recording medium for recording a program to embody the methods above. A method for ranked cleaning policy in file systems using flash memory, the method comprising the steps of: calculating rank values for all segments of the flash memory periodically; and if the storable space of the flash memory becomes less than a predetermined volume, a cleaner operating to clean invalid space of segments in order of their rank values obtained in the previous step high to low and thus to secure new storage space.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a cleaning policy and a method for recovering error in file systems; and, more particularly, to a ranked cleaning policy and an error recovery method in a file system using flash memory which can be used effectively and longer by dividing it into segments, adopting ranked cleaning policy and arranging its cleaned space evenly, and also the file system using the flash memory which can recover error quickly when sudden power error is caused by subdividing the erasing status, as well as a computer-based recording medium for recording a program to embody the methods above.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    The present invention concerns operating file systems using flash memories as media of recording and processing data in embedded systems such as information appliances, communication devices, set-top boxes, internet phones and the like.  
           [0003]    The embedded systems mentioned above should keep data when power is turned off. Even in sudden power-off, they should secure data consistency. Therefore, flash memories with non-volatile property are mostly used in the embedded systems.  
           [0004]    As information industry develops, embedded systems being developed lately refuse to stay as just simple electric devices and develop up to processing systems with a CPU inside. And more and more functions are required for these systems, making their structures more complex. This called for the real-time operating system (RTOS) to achieve the functions and to control and operate the devices, which are getting complex more and more, along with the need for file systems to run them.  
           [0005]    To effectively manage the flash memory in embedded systems, the present invention on a file system using flash memory has been developed as well as a new cleaning policy and error recovery method.  
           [0006]    Flash memories are stronger than other storage media, non-volatile, with fast access time, working with low electric power and small, which make them suitable for portable appliances. Flash memories have properties in common with EEPROM (Electrically Erasable Programmable ROM). That is, data in a flash memory can be deleted with electric signal and is reusable by programming or storing data therein again.  
           [0007]    However, there are three problems using flash memory as a storage medium.  
           [0008]    In the first place, once data are stored other data cannot be recorded therein until being cleaned. Secondly, taking 0.5-1 second to clean, it takes quite long time to delete data compared with reading time, 80 ˜150 nsec/byte, and storing time, about 10 μsec/byte. Thirdly, the number of times cleaning the flash memory is limited to about 100,000 times at normal temperature.  
           [0009]    So, to address the above problems, the number of times a flash memory is cleaned should be lessen as much as possible and the cleaning should be conducted on the memory space as evenly as possible while being cleaned. The space to be cleaned at a time is predetermined and fixed to be 64 Kbytes mostly. The space that can be cleaned at a time is called a segment.  
           [0010]    Among prior arts for solving the problem mentioned above are the U.S. Pat. No. 5,404,485 titled Flash File System and a paper under the tile of A Flash Memory Based File System published in the USEINX, pp 155 ˜164, in 1995.  
           [0011]    The patent of Flash File System concerns a flash file system for using flash memory as a form of a disk and describes the structure for storing data in the flash memory and a method for reading and controlling data stored therein. The patent calls the erase sector an erase unit (EU), and the EU is composed of a header, block allocation map (BAM) and data block region.  
           [0012]    The paper A Flash Memory Based File System describes a structure composing a file system with a flash memory and cleaning policy.  
           [0013]    The file system structure of the above dissertation names the memory space to be cleaned at a time a segment, and the segment consists of segment summery and data storage space. The memory storage space is divided into data blocks, which is generally 512 Kbytes, to store data on a block basis. Data blocks are called free blocks when the segment is cleaned, valid blocks when there are useful data, and invalid blocks when the data is not useful any more thus becoming blocks that should be cleaned.  
           [0014]    In the cleaning policy of the above prior art, Greedy method and Cost-benefit method are described. Greedy method selects a segment with least useful data block and cleans it prior to other segments, while Cost-benefit selects the segment to clean according to the formula shown below.  
               benefit   cost     =       age   ×     (     1   -   u     )         2      u               [     Formula                 1     ]                               
 
           [0015]    wherein u indicates the utilization coefficient of a segment, that is, the ratio of valid blocks in the segment, and  2   u  being the sum total of reading time and writing time that occur by transferring valid blocks in a segment to be cleaned to another segment, while age is the time that has passed since the block is converted into invalid block.  
           [0016]    The conventional technologies do not effectively address the shortcomings of limited number of times in cleaning a flash memory the cleaning time taken longer than reading or writing time. Also, in case of sudden power error while moving useful data from one block to another or conducting while cleaning, there was no way to recover the data or even if there is, other problems may occur performing it.  
           [0017]    The conventional cleaning procedures comprise the steps of searching free blocks in a destination segment that valid blocks in the segment to be cleaned will move into; copying the valid blocks in the segment to be cleaned into the free blocks found in the preceding step; converting the destination blocks into valid blocks; converting the source blocks into invalid ones; and cleaning the segment with the invalid blocks and converting it into a free segment.  
           [0018]    However, in case power error occurs in the second step there is no way to know whether copying has begun or the data are copied to the destination blocks because the destination blocks are in free status; when error has occurred in the midst of the copying procedure and then when you try to store data in this block again, error occurs because the destination block still remains in free status; and if power error is caused in the third step, the destination block where data are copied is converted to valid block and the source block still remains valid as well, so there is a problem that we do not know which one is normal data block.  
         SUMMARY OF THE INVENTION  
         [0019]    It is, therefore, an object of the present invention to provide ranked cleaning policy and a method for error recovery as well as a computer-based recording medium in file systems using a flash memory, which are capable of using the flash memory effectively and extending its life by segmenting the flash memory space, employing ranked cleaning policy and arranging spaces to clean evenly, and also capable of recovering error quickly caused by sudden power-off.  
           [0020]    In accordance with an embodiment of the present invention, there is provided a method for ranked cleaning policy in file systems using flash memory, the method comprising the steps of: a) calculating rank values for all segments of the flash memory periodically; and b) if the storable space of the flash memory becomes less than a predetermined volume, a cleaner operating to clean invalid space of segments in order of their rank values obtained in the previous step high to low and thus to secure new storage space.  
           [0021]    In accordance with an embodiment of the present invention, there is provided a method for power error recovery in file systems using flash memory, the method comprising the steps of: a) examining the block status for a segment of the flash memory and determining the type of blocks in instable status; b) if the results of the step a) shows the block of the segment is in allocated status, converting the status to the invalid status; c) if the results of the step a) shows the block of the segment is in prevalid status, converting the status to the valid status, and finding the source block for that block and if the source block is in valid status, converting it to invalid status; and d) if the results of the step a) shows the block of the segment is in erasing status, conducting the erasing procedure to the segment again.  
           [0022]    In accordance with an embodiment of the present invention, there is provided a computer-based recording medium for recording a program in file systems with a processor for conducting ranked cleaning policy, the functions of: a) calculating rank values for all segments of the flash memory periodically; and b) if the storage space of the flash memory become less than a predetermined volume, the cleaner operating to secure new space by cleaning invalid space of the segment in order of their rank value high to low.  
           [0023]    In accordance with an embodiment of the present invention, there is provided a computer-based recording medium for recording a program in file systems with a processor for power error recovery, the functions of: a) examining the block status of a segment of the flash memory and determining the type of blocks in instable status examined; b) if the results of the step a) shows the block of the segment is in allocated status, converting the status to the invalid status; c) if the results of the step a) shows the block of the segment is in prevalid status, converting the status to the valid status, and then finding its source block and if the source block is in valid status, converting it to the invalid status; and d) if the results of the step a) shows the block of the segment is in erasing status, conducting the erasing procedure to the segment again.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which:  
         [0025]    [0025]FIG. 1 is a configuration diagram showing a file system using flash memory in accordance with an embodiment of the present invention;  
         [0026]    [0026]FIG. 2 is a configuration diagram illustrating a flash memory used in a file system in accordance with an embodiment of the present invention;  
         [0027]    [0027]FIG. 3 shows a flow chart of a ranked cleaning policy method for error recovery in accordance with an embodiment of the present invention;  
         [0028]    [0028]FIG. 4 is a diagram showing a method for copying a segment in the cleaning policy procedures in accordance with an embodiment of the invention;  
         [0029]    [0029]FIG. 5 is a detailed flow chart illustrating a method for copying a segment in the cleaning policy procedures in accordance with an embodiment of the invention; and  
         [0030]    [0030]FIG. 6 depicts a flow chart of a method for recovering power error in an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter.  
         [0032]    [0032]FIG. 1 is a configuration diagram showing a file system using flash memory in accordance with an embodiment of the present invention.  
         [0033]    Providing the API (Application Program Interface) similar to UNIX, the file system interface  100  has extensibility of driving existing application programs almost as they are, offering consistence to users familiar with UNIX.  
         [0034]    The file system managing unit  101  provides system related functions such as generation, initialization and deletion of a file system, and such file-related functions as generation, initialization and deletion of a file. File system manager, for instance, makes the file system managing unit  101  support plural types of file systems by using the VFS (Virtual File System)  102 , which is developed by Sun Microsystems. The types of file systems supported here are the FAT (File Allocation Table)  103 , the UFS (Unix File System)  104 , the NFS (Network File System)  105 , the S5FS (System 5 File System), etc.  
         [0035]    In the meantime, with the buffer cache  107  placed in the lower part of the file system managing unit  101 , the number of times storing data in the flash memory is reduced, thus shortening access time to data stored therein.  
         [0036]    Buffer caches are originally used to improve response time and to process performance of a system by covering up the low speed of a disk. However, in file systems using flash memory of the present invention, these original effects of buffer caches are shrunken due to high speed of flash memories, but one thing still good is that the life span of a flash memory can be extended with this buffer cache.  
         [0037]    When utilizing the buffer cache, data are stored in a main memory buffer instead of the flash memory. And when accessing buffers they access to the buffer in the cache memory first, thus minimizing the number of time physically writing in the flash memory.  
         [0038]    Therefore, the number of times cleaning decreases, with overall access time getting faster and the life span of a flash memory being extended.  
         [0039]    The flash memory managing unit  108  performs the read/write function on the flash memory directly, and the FML (Flash Mapping Layer)  109  maps the logical address of file data to the physical address of the flash memory so it looks like the disk is in use to the upper layer. The region this mapping information is stored in is the BMT (Block Mapping Table) of the segment of FIG. 2, and when the mapping information is modified a new block is allocated and data are stored in the new block.  
         [0040]    The cleaner  110  performs function of making free segments in the flash memory  112  according to the cleaning policy and when power is turned off unexpectedly it recovers the data in the flash memory  112  consistently.  
         [0041]    [0041]FIG. 2 is a configuration diagram illustrating a flash memory used in the file system in accordance with an embodiment of the present invention.  
         [0042]    The space of the flash memory that can be cleaned at a time is fixed to a predetermined volume, and the number of times cleaning the flash memory is limited to about 100,000 times at normal temperature.  
         [0043]    As shown in FIG. 2, accordance with invention, the flash memory  112  comprises a number of segments  201 - 1 ,  201 - 2  . . .  201 -N. Generally, the space of the flash memory to be cleaned at one try is called a segment  201 , although there is a difference between manufacturers, generally one segment  201  is 128 Kbytes or 64 Kbytes wherein a sector block of a disk, which is usually 512 Bytes, can be stored several times. One segment can store 256 blocks normally.  
         [0044]    As seen in FIG. 2, read/write blocks  202  are allocated in the size of an ordinary sector.  
         [0045]    when the flash memory  112  is accessed, data is usually read and written as the unit of these read/write blocks  202 . When the blocks are erased, they are free. If data is stored in the blocks. And if data is useless, they become invalid blocks. The state of these blocks is expressed in a block mapping table (BMT)  204 .  
         [0046]    Each of the segments  201 - 1 ,  201 - 2  . . .  201 -N comprises a segment header  203 , a block mapping table  204 , a reserved region  205  and a data block  206 . The segment header  203  manages the information of its present status. And the block mapping table  204  administrates mapping information on logical addresses and physical addresses of the blocks stored in the segments  201 - 1 ,  201 - 2  . . .  201 -N and information on the status of the blocks.  
         [0047]    The reserved region  205  exists for adjusting the size of the blocks and no for other purposes. The remaining blocks are used for data blocks  206 . Regardless of being the block containing the segment header  203  or the one with the BMT when modified, the block in the segment  201  are stored in another free block.  
         [0048]    Information stored in the segment header  203  includes logical SN, the logical number of the present segment; block size, the size of a read/write block; the number of free blocks, the number of free block available; flags, flags on block allocation information and the like; the BMT offset, offset address for the location the BMT is stored in; segment status, status information for the recovery of power error caused while cleaning the segment; and erasing time, the time that has passed since the segment is cleaned.  
         [0049]    Information stored in the BMT  204  includes a logical block number, the number of the logical block for each physical block; and block status, the status of each block.  
         [0050]    In the BMT  204 , the read/write block is in one of free, valid, invalid, allocated, prevalid, bad and control statuses.  
         [0051]    Here, in the information on the block status, ‘free ’ means an empty block for new storage; ‘valid,’ a block containing useful data; ‘invalid,’ data in the block is not useful any more so they will be deleted later; ‘allocated,’ being used for recovery, the status before storage when valid data are yet copied before being copied; ‘prevalid,’ being used for recovery, but the status when valid data have been stored actually but not approved yet; ‘bad,’ unusable block; ‘control,’ a block for storing information for the BMT and the like.  
         [0052]    With this structure of a flash memory seen above, when there gets to be no more free block left after repeated storage and cleaning of data, some segment needs to be cleaned to arrange free blocks. So, the cleaner  110  should operate to keep a predetermined number of free segments before they fall below the number. This procedure is called cleaning policy.  
         [0053]    Unlike the conventional cleaning policy where the segment with most invalid blocks are cleaned, the present invention considers life span of the flash memory and presents ranked cleaning policy to distributing cleaned segments evenly in the flash memory.  
         [0054]    After calculating the rank value of each segment from the following formula 2, the ranked cleaning policy ranks the values of segments high to low and cleans as many segments as needed.  
             R   =     A          age   ·   i       2        v   ·   f                   [     Formula                 2     ]                               
 
         [0055]    Here, v is the ratio of valid blocks to the entire segment;  2   v , the cost for reading and moving a valid block it to another segment; f, the ratio of free blocks; i, the ratio of invalid blocks; and age, the time that has passed since the segment is cleaned.  
         [0056]    Also, A, the weight for i/f, determines where to put relative importance between invalid blocks and valid blocks. When performing cleaning, free blocks are used without going through cleaning procedures. If the flash memory has still long life, the A value can be made big to put relative importance on the i value, but if it has short life, the A value can be made small putting importance on the f value in order to make full use of free blocks.  
         [0057]    Using the R values calculated from the formula 2, cleaning procedure begins to perform on the segment with the biggest R value.  
         [0058]    Here, one thing to mind is that to clean a segment its valid blocks should be moved to free blocks of another segment. This means that there should be sufficient amount of other free segments and free blocks. So, in case the number of free segments is less than a predetermined volume, N 2 , the cleaner should operate to keep more than N 2  number of free segments. This procedure is conducted repeatedly at regular intervals, or if the flash memory stops not being used for a predetermined time, it is considered to be idle time and the cleaner operates to clean a segment.  
         [0059]    However, when the number of free segments decreases and becomes less than a predetermined number N 1 , free segments should be made quickly. When N 2  numbers of free segments are not secured by this ranked cleaning policy, the flash memory is considered to have reached its limit.  
         [0060]    The ranked cleaning policy has the cleaner check the number of free segments periodically when data is stored in the flash memory.  
         [0061]    If there are more than N 2  numbers of free segments the ranked cleaning policy is not performed and thus the cleaner does not operate. If there are less than N 2  numbers of free segments, the ranked cleaning policy is performed and thus the cleaner operates. Here, rank values R are calculated for each segment, and the cleaning procedure is performed first to the segment with the biggest rank value. When free segments are generated more than N 2 , the cleaning procedure finishes.  
         [0062]    [0062]FIG. 3 shows a flow chart of ranked cleaning policy method for error recovery in accordance with an embodiment of the present invention.  
         [0063]    At step  301 , periodically or when the system is idle, the cleaner operates.  
         [0064]    First, at step  302 , the cleaner figures out the number of free segments N fs  among the segments of the flash memory, and at step  303 , sees if the number of free segments N fs  is less than N 2 .  
         [0065]    At step  304 , if the number of free segments N fs  turns out to be more than N 2 , the procedure terminates because there is enough space.  
         [0066]    At step  305 , if the number of free segments N fs  turns out to be less than N 2 , the procedure of cleaning segments is conducted, checking if there are segments with invalid blocks to be cleaned, because there is no space enough to store new data in the flash memory.  
         [0067]    At step  306 , if the result of the step  305  shows no segments with invalid blocks, which means there is no segment to clean, the cleaner compares N fs  with N 1  which is the minimum number of segments for moving blocks, and sees if the flash memory is full. At step  307 , if N fs  turns out to be smaller than N 1  (N fs &lt;N 1 ), a message requesting to take necessary steps is sent to the user instantly because the flash memory is full. If N fs  turns out to be bigger than N 1  (N fs &gt;N 1 ), the cleaner stops operating because there is space yet in the flash memory and has the remaining flash memory space used.  
         [0068]    At step  308 , in case the result of the step  305  shows presence of invalid blocks, rank values R for all segments are calculated.  
         [0069]    At step  309 , the segment with the largest rank value S src  is searched for, and the oldest segment S dst  with sufficient space to accommodate valid blocks of the source segment S src  is selected in order to clean the segment with the biggest rank to be a free segment. At step  310 , valid blocks of the S src  are moved to the oldest segment S dst  and at step  311  the S src  is cleaned.  
         [0070]    Then, going back to step  303  and it is checked if there is sufficient space in the flash memory again.  
         [0071]    The ranked cleaning policy described above maximizes life span of a flash memory by extending segment-cleaning time as much as possible and arranging cleaned segments evenly in the flash memory.  
         [0072]    [0072]FIG. 4 is a diagram showing a method for copying a segment in the cleaning policy procedures in accordance with an embodiment of the invention.  
         [0073]    As shown in FIG. 4, the present invention adds allocated and prevalid statuses for blocks to the procedure of copying valid blocks to make error recovery done easily.  
         [0074]    First at step  401 , to clean a segment, a free block where the source valid block will be moved is searched for, and it is converted to the allocated status.  
         [0075]    At step  402 , the original data are copied to the destination block in the allocated status, and the destination block is converted to the prevalid status.  
         [0076]    At step  403 , as the source block is copied without any trouble and becomes unnecessary any more, it should be converted to the invalid status. At step  404 , as the destination block has the data coming from the source block, it is now converted to the valid status.  
         [0077]    At step  405 , after the steps  401  to  404  are performed for all the valid blocks in the segment to be cleaned, the procedure of cleaning segment is conducted.  
         [0078]    At step  406 , the cleaned segments are converted to free segments.  
         [0079]    [0079]FIG. 5 is a detailed flow chart illustrating a method for copying a segment in the cleaning policy procedures in accordance with an embodiment of the invention.  
         [0080]    First at step  501 , all blocks of the source segment S src  are in valid status and the target segment S dst  has sufficient free blocks.  
         [0081]    At step  502 , to move valid blocks of the source segment S src  thereto one by one, free blocks B dst  are searched for in the destination segment S dst , and at step  503  the free blocks B dst  found are converted to the allocated status.  
         [0082]    At step  504 , one valid block B src  of the source segment S src  is copied to the block converted to the allocated status B dst  , and then the B dst  is converted to the prevalid status. At step  505 , the status of the source block B src  is turned invalid, and then at step  506  the B dst  is converted to the valid status.  
         [0083]    The reason going through as many steps as shown above is to distinguish in what step power error occurs when it is caused.  
         [0084]    At step  507 , it is checked whether there are valid blocks left in the source segment S src  , as it has to be cleaned.  
         [0085]    If the check result shows any valid blocks left in the source segment S src  , the procedure returns to step  502 , taking the steps from  502  to  506  in order to move out all the valid blocks left.  
         [0086]    At step  508 , if the check result shows no valid blocks left in the source segment S src  , the segment is cleaned. As this step concerns erasing, the blocks in this segment are converted to the erasing status.  
         [0087]    At step  509 , after cleaning all the blocks in the source segment S src  , they become to be in the free status.  
         [0088]    [0088]FIG. 6 depicts a flow chart of a method for recovering power error in an embodiment of the present invention.  
         [0089]    In case power error occurs in the cleaning procedures of FIGS. 4 and 5, the appliance adopting the flash memory file system gets restarted, checking the segment status of the flash memory, and according to the checked condition, it conducts recovery procedures as following.  
         [0090]    When error occurs in step  401  of FIG. 4, the source block is in valid status and the destination block is in free status so you just leave them as they are.  
         [0091]    When error occurs in the step  402 , the destination block is in allocated status and wrong data may be in the destination block because the original data were being copied. So, the destination block needs to be converted to the invalid status, leaving the source block in valid status as it is. Later the source block should be moved to another free block.  
         [0092]    When error occurs in the step  403 , the destination block is in valid status and the destination block is in prevalid status. With the original data all having been copied to the destination block, the source block should be converted to the invalid status while the destination block is turned to the valid status.  
         [0093]    When error occurs in the steps  404  to  406 , the destination block is in invalid status and the destination block falls in either prevalid or valid status with all the original data that have been copied. The source block, which has become invalid takes cleaning steps and the destination block should be changed valid.  
         [0094]    Referring to FIG. 6, the power error recovery procedures above will be described in detail hereinafter.  
         [0095]    At step  601 , when an appliance gets restarted due to power error, it examines the block status of all segments in the flash memory.  
         [0096]    At step  603 , it is checked if there are blocks in instable statuses such as allocated, prevalid and erasing statuses other than normal and stable statuses, e.q., free, valid and invalid statuses.  
         [0097]    If the check result shows no instable block, the procedures terminates because there is no object to recover. At step  604 , if there are blocks in one of the three instable statuses, it is first checked if it is in allocated status.  
         [0098]    In case that instable status is allocated status, the destination block should be converted invalid because the allocated status means error has occurred in the middle of copying data from the source block, and after invalidating the data at step  605 , the procedures return to the step  603  and check again if there are blocks in instable status at step  603 .  
         [0099]    Secondly, at step  606  it is checked if the instable status is the prevalid status. If it is, the original data have been all copied and the destination block is in the course of being converted from valid to invalid status. So, at step  607  the prevalid status should be converted to the valid status and finding the source block, if it is still valid, it should be changed to be invalid, otherwise, at step  608  leave it as it is. This is the case when error has occurred in the step  403  or  404  of FIG. 4.  
         [0100]    Finally, at step  609  it is checked if there are blocks in erasing status and if there are, the erasing procedures should be performed again because error has occurred which erasing the segment.  
         [0101]    The above procedures should be performed as long as instable blocks are found out.  
         [0102]    The error recovery method as described above is applicable to embedded systems, which have high chances of sudden power error and have to keep data after power is turned off. That is, it can be comprehensively applied to copying or storing data in flash memories, EEPROM and the like.  
         [0103]    The present invention described above can be embodied in a program and stored in a computer-based recording media such as CD ROMs, RAMs, ROMs, floppy disks, hard disks, optical magnetic disks and so on.  
         [0104]    The present invention presents a file system structure employing a flash memory and describes the method of storing data in the flash memory of the file system.  
         [0105]    The present invention can extend life span of a flash memory by segmenting it and adopting ranked cleaning policy, and improves the speed of the overall file system by using the space of the flash memory evenly and reducing the number of times cleaning it.  
         [0106]    Also, while conducting the ranked cleaning policy, this invention prevents data damage by recovering the error of inconsistency caused by sudden power-off in operation, which makes us to use data in embedded systems more safely and confidently.  
         [0107]    While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.