Abstract:
The invention provides a hub document preparation method which collects a plurality of external files and attachment files to be included in a structured document of a hub document format to allow a hub document to be prepared readily, to reduce the burden to a document preparing person, and to augment the operation and efficiency of preparing a hub document.

Description:
BACKGROUND OF THE INVENTION 
   1) Field of the Invention 
   This invention relates to a hub document preparation method for preparing a single structured document of the hub document format such as, for example, an SGML (Standard Generalized Markup Language) document from a plurality of non-structured documents such as, for example, documents prepared on a word processor. 
   2) Description of the Related Art 
   Various structured documents are conventionally known and include an SGML (Standard Generalized Markup Language) document and an XML (Extended Markup Language) document in which document contents are represented in a text format excluding layout information and so forth from document data. Such structured documents as an SGML document and an XML document allow definition of a logical structure of the document by adding a mark called tag for identifying the structure of the document and are progressively spread as standard language documents for storage/search or exchange of a document. 
     FIG. 8  illustrates a structure of an SGML document. In the following, a structured document is described taking an SGML document as an example with reference to  FIG. 8 . 
   Generally, an SGML document  20  is composed of an SGML declaration  21  which describes various references such as types of codes used in the document, a DTD (Document Type Definition)  22  which defines mutual relationships of document elements, that is, a document structure, and a document instance  23  representative of document contents. 
   The DTD  22  defines tags to be applied to elements of the document such as an index, the body of the document, and a list. More particularly, the DTD  22  includes element declarations which define the elements of the document, relationships of inclusion of elements, an order in which the elements are to be arranged, a number of times of appearance of each element and so forth, attribute declarations which define attributes of the elements, entity declarations which declare methods of taking special characters, pictures or the like into the document, and so forth. The DTD  22  allows definitions of memberships, an order of appearance, numbers of times of appearance and so forth of tags in a tree structure. 
   In order to prepare the SGML document  20 , a document structure of the SGML document  20 , that is, the DTD  22 , is prepared or acquired first, and then the document instance  23  which fits with the DTD  22  is prepared. 
   The document instance  23  may have a graphic file, which includes graphic information, or a like file attached thereto. In the following description, a file attached to the document instance  23  in this manner is referred to as attachment file. 
   Upon preparation of the SGML declaration  21  or the DTD  22 , various definition contents (declarations and so forth) may be described directly in the SGML declaration  21  or the DTD  22  as described above, or such definition contents may be described in an external file (external entity)  21   a  or  22   a  stored in an external area  25  in advance such that the external file  21   a  or  22   a  may be designated by the SGML declaration  21  or DTD  22  (external entity declaration). 
   Though not illustrated in  FIG. 8 , upon preparation of the document instance  23 , document contents of the document instance  23  may be described in an external file in advance so as to allow the external file to be designated by the document instance  23  of the SGML document  20  (external entity declaration) similarly as upon preparation of the SGML declaration  21  or DTD  22 . 
   The external file designated by the external entity declaration by the document instance  23  may have an attachment file attached thereto. In this instance, an external entity declaration for declaring the entity of the attachment file is prepared. 
     FIG. 9  illustrates a structure of an SGML document (hub document format structured document)  30  of the hub document format. Referring to  FIG. 9 , contents of an SGML declaration and a DTD are prepared and described in external files (external entities)  31  and  32 , respectively, while a plurality of (two in  FIG. 9 ) document contents (document instances) are prepared and described in external files  33   a  and  33   b , respectively, and the external files  31 ,  32 ,  33   a  and  33   b  are designated (external entity declaration) by a hub document  35  to prepare the single SGML document  30  of a hub document format. 
   The SGML document  30  of such a hub document format as described above is suitable as a document wherein document contents are described in detail in a great number of parts, for example, such as a maintenance manual or the like, and is generally suitable to combine contents (instances) of a plurality of documents prepared on a word processor or a like document preparing system into a single SGML document such as the SGML document  30 . 
   It is to be noted that an authoring tool in most cases prepares one SGML document by adding an SGML declaration and a DTD to one document instance (one file) as seen in  FIG. 8 . 
   Upon preparation of such a hub document  35  as described above, the preparing person first collects a plurality of external files to be included into the SGML document  30  of the hub document format, and then prepares entity declarations (ENTITY statements) for individually referring to the entities of the external files. 
   However, in such a conventional hub document preparation method as described above, in order to designate the external files with the external entity declarations, the preparing person must collect necessary external files. 
   For example, in order to designate the external files  31 ,  32 ,  33   a  and  33   b , which are discretely located on the computer system and in which document instances and so forth are stored individually, with external entity declarations, the external files  31 ,  32 ,  33   a  and  33   b  must be located after the stored locations of them are checked. Therefore, the conventional hub document preparation method described above has a subject to be solved in that the operation just described is cumbersome and makes a heavy burden to the preparing person, and besides much time is required for the preparation of the hub document  35  and the operation efficiency is low. 
   Further, where a document instance has an attachment file such as a graphic file added thereto, in order to prepare an entity declaration (ENTITY statement) for referring to the entity of the attachment file, not only an external file of the document instance must be collected but also the stored location of the attachment file must be checked to collect the attachment file. Consequently, the conventional hub document preparation method described above has another subject to be solved in that the presence of such an attachment file as described above further increases the burden to the preparing person and increasing time is required for preparation of the hub document  35  and besides the operation efficiency is deteriorated. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a hub document preparation method which facilitates collection of a plurality of external files and attachment files to be included in a structured document of a hub document format to allow a hub document to be prepared readily to reduce the burden to a document preparing person and augment the operation efficiency. 
   In order to attain the object described above, according to the present invention, there is provided a hub document preparation method for preparing a hub document which describes entity declarations for referring to entities of a plurality of structured documents individually corresponding to a plurality of non-structured documents in order to prepare a single hub document format structured document from the plurality of non-structured documents, comprising the steps of setting in advance an original document storage area for storing the non-structured documents and a structured document storage area for storing structured documents obtained by conversion of the non-structured documents, storing, each time one of the plurality of non-structured documents to be included in the hub document format structured document is prepared or edited, the non-structured document into the original document storage area, converting the non-structured documents stored in the original document storage area into structured documents and storing the structured documents into the structured document storage area, acquiring document names of the plurality of structured documents stored in the structured document storage area and preparing entity declarations for referring to entities of the structured documents, and preparing the hub document based on the entity declarations regarding the structured documents. 
   The hub document preparation method may be constructed such that, in addition to the original document storage area and the structured document storage area, an attachment file storage area for storing attachment files attached to the non-structured documents and entity declarations regarding the attachment files is set in advance, and, upon preparation or editing of any of the plurality of structured documents to be included in the hub document format structured document, if an attachment file is attached to the non-structured document, then the attachment file is stored into the attachment file storage area and an entity declaration for referring to an entity of the attachment file is prepared and stored into the attachment file storage area, and then the entity declarations regarding the attachment files stored in the attachment file storage area are extracted and the hub document is prepared based on the entity declarations regarding the attachment files and the entity declarations regarding the structured documents. 
   Alternatively, the hub document preparation method may be constructed such that, in addition to the original document storage area and the structured document storage area, an attachment file storage area for storing attachment files attached to the non-structured documents and an entity declaration storage area for storing entity declarations regarding the attachment files are set in advance, and, upon preparation or editing of any of the plurality of non-structured documents to be included in the hub document format structured document, if an attachment file is attached to the non-structured document, then the attachment file is stored into the attachment file storage area and an entity declaration for referring to an entity of the attachment file is prepared and stored into the attachment file storage area, and then the entity declarations regarding the attachment files stored in the entity declaration storage areas are extracted and the hub document is prepared based on the entity declarations regarding the attachment files and the entity declarations regarding the structured documents. 
   The entity declarations of the structured documents may have file names same as file names of the original non-structured documents individually corresponding to the structured documents. The entity declarations regarding the attachment files stored in the entity declaration storage area may have file names same as file names of the non-structured documents to which the attachment files are attached. The attachment files may be graphic files each of which includes graphic information. 
   The structured documents may be Standard Generalized Markup Language documents whose document structure is defined by a Document Type Definition. 
   With the hub document preparation method described above, the following advantages can be anticipated. 
   1) Since only it is required upon preparation of a hub document to refer to a predetermined storage area or areas, a hub document can be prepared rapidly and readily, and the operation burden to a preparing person is light and a high operation efficiency can be achieved. 
   2) Since a hub document can be prepared automatically, it can be prepared rapidly and readily, and the operation burden to the preparing person is light and a high operation efficiency can be achieved. 
   3) Since, from document names of structured documents stored in the structured document storage area, entity declarations for referring to the entities of the structured documents or entity referring statements for referring to the entities of the structured documents can be prepared readily, a hub document can be prepared rapidly and readily, and the operation burden to the preparing person is light and a high operation efficiency can be achieved. 
   4) Since, upon editing of a structured document, the structured document of the object of editing can be searched out readily from the structured document storage area, such structured documents can be managed readily. 
   5) Since, upon preparation of a hub document, an entity declaration stored in the attachment file storage area can be extracted readily, the hub document can be prepared rapidly and readily, and the operation burden to the preparing person is light and a high operation efficiency can be achieved. 
   6) When, upon editing of a hub document, an attachment file used is to be edited or in a like case, the attachment file of the object of editing can be searched out readily from the attachment file storage area, and consequently, a high operation efficiency can be achieved in the editing operation. 
   7) Since an entity declaration for referring to the entity of an attachment file can be prepared automatically, the operation burden to the preparing person is further decreased and the working efficiency is augmented. 
   8) Since, upon preparation of a hub document, an entity declaration stored in the entity declaration storage area can be extracted readily, the hub document can be prepared rapidly and readily, and the operation burden to the preparing person is light and a high operation efficiency can be achieved. 
   9) Since, when editing, search for bugs or the like of a hub document is performed, an entity declaration or the like regarding a desired non-structured document can be searched out readily, a high working efficiency can be achieved in the operation. 
   10) Since, when editing, search for bugs or the like of a hub document is performed, an entity declaration or the like regarding a desired attachment file can be searched out readily, a high working efficiency can be achieved in the operation. 
   11) A hub document including a graphic file can be prepared readily. 
   12) An SGML document of a hub document format can be prepared rapidly and readily. 
   The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic view illustrating a hub document preparation method according to an embodiment of the present invention; 
       FIG. 2  is a block diagram showing a configuration of a system (computer system) to which the present invention is applied; 
       FIG. 3  is a diagrammatic view showing a structure of a directory formed on a hard disk of the system (computer system); 
       FIG. 4  is a flow chart illustrating the hub document preparation method according to the embodiment of the present invention; 
       FIG. 5  is a schematic view showing an example of a screen display of a display unit of the system (computer system); 
       FIG. 6  is a view showing an example of a description of a hub document prepared by the hub document preparation method of the embodiment of the present invention; 
       FIG. 7  is a diagrammatic view illustrating a modification to the hub document preparation method according to the embodiment of the present invention; 
       FIG. 8  is a diagrammatic view showing a structure of an SGML document; and 
       FIG. 9  is a diagrammatic view showing a structure of an SGML document (hub document) of a hub document format. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  illustrates a hub document preparation method according to an embodiment of the present invention.  FIG. 2  illustrates a configuration of a system (computer system  10 ) to which the present invention is applied.  FIG. 3  shows a structure of a directory formed on a hard disk  12  of the system. 
   Referring first to  FIG. 2 , the computer system shown is generally denoted at computer system  10  and includes a CPU (Central Processing Unit)  11 , a hard disk  12 , a memory  13 , an interface  14 , a keyboard  15 , a mouse  16 , a display unit  17  and a bus  18 . The computer system  10  is used to prepare an SGML (Standard Generalized Markup Language) document which is a kind of structured document. 
   The computer system  10  has a function as a word processor and stores a word processor document (non-structured document) prepared by the word processor using the keyboard  15  and the mouse  16  onto the hard disk  12 . 
   It is to be noted that, in the present embodiment, the MS-Word of Microsoft is used as the word processor. However, the word processor is not limited to this and any suitable word processor may be used as such. 
   The memory  13  is an area to be used for expansion of data and so forth when the CPU  11  performs various arithmetic processes, and is formed from, for example, a RAM (Random Access Memory) or a like element. 
   The interface  14  allows communication of data between the computer system  10  and an external apparatus and is formed from, for example, a communication port or a like element. 
   The keyboard  15  and the mouse  16  serve as inputting means for being operated by a preparing person of an SGML document to input a document, various instructions and so forth and perform selection and so forth therethrough. The display unit  17  displays a result of arithmetic processing by the CPU  11 , an SGML document being prepared and so forth. 
   The hard disk  12  stores various data and other necessary information, and a hub document  100  prepared in such a manner as hereinafter described and SGML documents of the hub document format (hub document format structured documents) prepared based on the hub document  100  are recorded onto the hard disk  12 . It is to be noted that an SGML document of the hub document format is hereinafter referred to as hub document format SGML document. 
   An SGML document (hub document format SGML document) is a structured document prepared in accordance with a predetermined DTD (Document Type Definition) and, for example, is recorded on the hard disk  12  and includes an SGML declaration, a DTD and a document instance. 
   The SGML declaration describes various references regarding a type of a character code used in the document, determination of whether or not an end tag can be omitted, and so forth. The document instance represents contents of the document. 
   The DTD defines a structure of the document and gives arbitrary significance to document structure elements to define the document structure elements, and describes an order of appearance of the document structure elements, hierarchical relationships between different document structure elements, a number of times of repetition of each document structure element, and so forth. The DTD defines elements which form the document and mutual relationships of the elements, that is, hierarchical relationships and referencing relationships, using an element declaration (ELEMENT statement) and/or an entity declaration (ENTITY statement). 
   In the hub document  100  prepared by the hub document preparation method of the present embodiment, similarly as in the hub document  35  shown in  FIG. 8 , contents of the SGML declaration and the DTD are prepared and described in external files (external entities), and an SGML document of a hub document format is prepared by designating one of the external files (external entity declarations). 
   The external files which describe contents of the SGML declaration and the DTD are stored on the hard disk  12 . 
   Referring now to  FIG. 1 , the hard disk  12  has formed thereon an original document storage area  1  for storing a non-structured document, a structured document storage area  2  for storing a structured document obtained by conversion of the non-structured document, and an attachment file storage area  3  for storing, where the non-structured document has an attachment file attached thereto, the attachment file and an entity declaration regarding the attachment file. 
   More particularly, the hard disk  12  has formed thereon as shown in  FIG. 3  directories such as a book 1  directory D 1  and a book 2  directory D 2  for individual SGML documents to be prepared. Such book 1  directory D 1  and book 2  directory D 2  are set in advance by a preparing person or the like. 
   Each of the directories such as the book 1  directory D 1  and the book 2  directory D 2  has a source directory D 3 , an sgml directory D 4  and a graphic directory D 5  formed therein. 
   The source directory D 3  is provided for storing a document format (non-structured document) unique to the word processor before conversion and functions as the original document storage area  1  shown in  FIG. 1 . The sgml directory D 4  stores an SGML document (document instance; structured document) obtained by conversion of the word processor document (non-structured document) and functions as the structured document storage area  2  shown in  FIG. 1 . 
   The graphic directory D 5  stores, where a graphic file is attached (added) to the word processor document before conversion into an SGML document, a copy of the file (graphic file) attached and stores an entity declaration regarding the graphic file added to the word processor document as hereinafter described, and functions as the attachment file storage area  3  shown in  FIG. 1 . It is to be noted that a file attached to a word processor document is hereinafter referred to as attachment file. 
   The CPU  11  performs various arithmetic processing and SGML document preparation processing using data stored on the hard disk  12  and the memory  13  in accordance with instructions inputted from the keyboard  15  and the mouse  16 , and controls the interface  14 , the display unit  17  and other pertaining components. 
   Further, upon preparation of the hub document  100 , the CPU  11  sets the original document storage area (source directory D 3 )  1 , the structured document storage area (sgml directory D 4 )  2  and the attachment file storage area (graphic directory D 5 )  3  in advance on the hard disk  12 . Furthermore, each time a preparing person prepares or edit a non-structured document on the word processor, the CPU  11  stores the thus prepared non-structured document into the source directory D 3 . In addition, if the non-structured document has an attachment file added thereto, then the CPU  11  stores the attachment file into the attachment file storage area (graphic directory D 5 )  3 , and prepares an entity declaration for referring to the entity of the attachment file and stores the prepared entity declaration as an ENTITY file into the attachment file storage area (graphic directory D 5 )  3 . 
   When an entity declaration regarding an attachment file is stored as an ENTITY file into the graphic directory D 5 , the CPU  11  uses, for the file of the entity declaration (ENTITY FILE) a file name same as the file name of the word processor document (non-structured document) to which the attached document is attached. Further, the CPU  11  uses, for the entity declaration regarding each structured document, a file name same as the file name of the original word processor corresponding to the structured document. 
   Further, the CPU  11  converts a plurality of non-structured documents stored in the source directory D 3  into SGML documents, stores the SGML documents after the conversion into the sgml directory D 4 , acquires file names (document names) of the plurality of SGML documents stored in the sgml directory D 4  and prepare entity declarations for referring to the entities of the individual SGML documents. 
   Then, the CPU  11  extracts entity declarations regarding attachment files stored as ENTITY files in the graphic directory D 5  and prepares the hub document  100  based on the entity declarations regarding the SGML documents and the entity declarations regarding the attachment files. 
   Further, in the present embodiment, the CPU  11  executes a program stored on the hard disk  12  to perform the processes described above to prepare the single hub document  100  from a plurality of non-structured documents. For example, a macro of a word processor, add-on software or the like functions as such program. 
     FIG. 6  illustrates an example of description of the hub document  100  prepared by the hub document preparation method of the present embodiment. Referring to  FIG. 6 , the hub document  100  illustrated declares and refers as external entities to contents described in an external file of front.sgm under the entity name “front.sgm”, contents described in another external file of t0000010.sgm under the entity name “t0000010.sgm”, graphic data stored in an attachment file of danger.gif under the entity name “danger.gif”, graphic data stored in another attachment file of warning.gif under the entity name “danger.gif, graphic data stored in a further attachment file of caution.gif under the entity name “caution.gif”, and graphic data stored in a still further attachment file of FUJITSU.gif under the entity name “FUJITSU.gif”. 
   Further, the hub document  100  illustrated in  FIG. 6  refers (external entity reference) to, as document instances, contents described in an external file of front.sgm under the entity name “front.sgm” and contents described in another external file of t0000010.sgm under the entity name “t0000010.sgm”. 
   It is to be noted that the hub document  100  (a hub document format SGML document) prepared by the present method may be recorded not only onto the hard disk  12  but also to various recording media including a flexible disk, a CD-ROM, an optical disk, a magneto-optical disk and a magnetic tape in a similar manner as in the present embodiment and transported or stored as such. 
   Subsequently, the hub preparation method of the present embodiment executed on the computer system  10  having the construction described above is described specifically with reference to a flow chart (steps S 1  to S 4 ) shown in  FIG. 4 . 
   In the present embodiment, processes in steps S 1  to S 4  described below are performed to prepare the hub document  100  for preparing a single hub document format SGML document from a plurality of non-structured documents prepared on a word processor. 
   The processes in steps S 1  to S 4  are executed by execution of programs stored on the hard disk  12 . According to the programs, icons B 1  to B 5  for execution of such programs are displayed on a display screen  17   a  of the display unit  17  such that the preparing person can select any of the icons B 1  to B 5  to perform desired processing. It is to be noted that the hub document  100  to be prepared may sometimes be referred to simply as document. 
   In order to prepare the hub document  100 , the preparing person first uses the keyboard  15 , mouse  16  and so forth to select the “document setting” icon B 1  to effect document path setting (step S 1 ). 
   The document path setting is a process for linking the document name of a document to be prepared (the hub document  100 ) and a directory for storage of the prepared document with each other and, for example, a process of linking the book 1  directory D 1  or the book 2  directory D 2  illustrated in  FIG. 3  and a name of the document to be prepared. More specifically, in the document path setting, the preparing person inputs a document name and a directory (document path) corresponding to the document name in accordance with instructions displayed on the display screen  17   a  of the display unit  17 . 
   Then, the document preparing person uses the mouse  16  and so forth to select the “card preparation” icon B 2  or the “card editing” icon B 3  to perform document preparation/editing of the document (step S 2 ). 
   The document preparation/editing is preparation and/or editing of a non-structured document on the word processor. In the present embodiment, the document names set in step S 1  are displayed on the display screen  17   a , and the preparing person selects a document to be prepared or edited from among the documents and then prepares a word processor document which forms the selected document. 
   If the preparing person adds, upon preparation of the word processor document, a graphic file to the word processor document by executing a cut-and-paste operation of an attachment file such as a graphic file to the word processor document, then the CPU  11  copies the added graphic file into the book 1  directory D 1  (attachment file storage area  3 ), prepares an ENTITY statement for declaring the entity of the graphic file, and stores the ENTITY statement as an ENTITY file having a file name same as the file name of the non-structured document to which the graphic file is added into the graphic directory D 5  (attachment file storage area  3 ). 
   For example, if the preparing person pastes a graphic file named “danger.gif” to a word processor document having a file name of “front.doc”, then the CPU  11  copies the graphic file named “danger.gif” into the graphic directory D 5 , prepares an ENTITY statement for declaring the entity of the graphic file named “danger.gif” (for example, ‘&lt;!ENTITY danger.gif system “danger.gif” ndata GIF&gt;’), and stores the ENTITY statement as an ENTITY file named “front.ent” into the graphic directory D 5 . 
   Further, if another attachment file is added to the word processor document (front.doc) later, then each time an attachment file is added, an ENTITY statement for declaring the entity of the attachment file is added to the ENTITY file named “front.ent”. 
   It is to be noted that, when the preparing person selects a document to be prepared or edited, copies of word processor documents and graphic files and so forth produced before the document preparation/editing is completed are stored into the respective directories (source directory D 3 , sgml directory D 4  and graphic directory D 5 ) formed in the directory (for example, book 1  directory D 1 ) designated in step S 1 , but are not stored into the directories (source directory D 3 , sgml directory D 4  and graphic directory D 5 ) of any other document (the book 2  directory D 2 ). 
   The preparing person having prepared required word processor documents (non-structured documents) uses the mouse  16  or the like to select the “WORD SGML batch conversion” icon B 4  to convert the prepared non-structured documents into SGML documents (step S 3 ). 
   More particularly, the CPU  11  converts all of the non-structured documents stored in the source directory D 3  into SGML documents and stores all of the thus prepared SGML documents as SGML documents having file names same as the file names of the respective original non-structured documents into the sgml directory D 4 . 
   For example, if a non-structured document named “front.doc” is stored in the source directory D 3 , then the CPU  11  converts the document “front.doc” into an SGML document (SGML instance) and stores the SGML document after the conversion into the sgml directory D 4  with the name “front.sgm” added to the same. 
   Then, the preparing person uses the mouse  16  or the like to select the “hub document preparation” icon B 5  to automatically prepare a hub document (step S 4 ). 
   The automatic preparation of a hub document in step S 4  is performed in accordance with a process including the following steps  1 ) to  4 ). 
     1 ) The CPU  11  first acquires a list of file names of the SGML instances stored in the sgml directory D 4  and prepares an ENTITY statement regarding each of the SGML instances. 
   For example, if a file named “front.sgm” is stored in the sgml directory D 4 , then the CPU  11  prepares an ENTITY statement (for example, ‘&lt;!ENTITY front.sgm system “front.sgm”&gt;’) for declaring the entity of the file “front.sgm”. 
     2 ) Then, the CPU  11  successively extracts the ENTITY statements prepared in step S 2  and stored in the ENTITY files of the graphic directory D 5  and adds them to the last ends of the ENTITY statements prepared in  1 ) above. 
   For example, the CPU  11  adds an ENTITY statement ‘&lt;!ENTITY danger.gif system “danger.gif” ndata GIF&gt;’stored in an ENTITY file named “front.ent” in the graphic directory D 5  to the last end of the ENTITY statement prepared in  1 ) above. 
     3 ) Further, the CPU  11  adds an entity reference statement for referring to the entity of an SGML instance stored in the sgml directory D 4 , as a document instance of the hub document  100 , to the last end of the ENTITY document added in  2 ) above. 
   For example, if an SGML instance named “front.sgm” is stored in the sgml directory D 4 , then the CPU  11  adds an entity reference statement (&amp;front.sgm;). 
     4 ) Then, a DOCTYPE declaration statement is added to the top of the hub document prepared in  1 ) to  3 ) above. 
   It is to be noted that the DOCTYPE declaration statement may be prepared as a fixed prototype in advance. 
   In this manner, according to the hub document preparation method as the embodiment of the present invention, a directory such as the book 1  directory D 1  and the book 2  directory D 2  is formed for each SGML document to be prepared on the hard disk  12 , and the source directory D 3 , sgml directory D 4  and graphic directory D 5  are formed in each of the book 1  directory D 1  and the book 2  directory D 2 . Further, a document (non-structured document) of a document format unique to a word processor before conversion is stored into the source directory D 3  whereas an SGML document (document instance) after conversion is stored into the sgml directory D 4 . Furthermore, where an attachment file is to be added to the word processor document before the conversion into an SGML document, a copy of the attachment file is stored into the graphic directory D 5 . Consequently, upon preparation of the hub document  100 , the CPU  11  is required only to refer to predetermined directories. Consequently, the hub document  100  can be prepared readily at a high speed. 
   In particular, from a list of file names of SGML instances stored in the sgml directory D 4 , an ENTITY statement or an entity reference statement regarding each SGML instance can be prepared readily. Further, since all attachment files to be referred to by the SGML instances are stored in the graphic directory D 5 , the attachment files can be managed readily. 
   For example, when it is intended to edit a graphic file used in the hub document  100  upon editing of the hub document  100  or the like, the attachment file of the object of editing can be searched out readily from the graphic directory D 5 . Also when it is intended to edit an SGML instance, the SGML instance of the object of editing can be searched out readily from the sgml directory D 4 . 
   Further, when, upon preparation of a word processor document, an attachment file such as a graphic file is patched to the word processor document to add the graphic file to the word processor document, the CPU  11  prepares an ENTITY statement for declaring the entity of the graphic file, stores the ENTITY statement as an ENTITY file having a file name same as the file name of the word processor document, to which the graphic file is added, into the graphic directory D 5 , and extracts, upon preparation of the hub document  100 , the ENTITY statement stored in the ENTITY file. Consequently, the hub document  100  can be prepared readily and rapidly. 
   Furthermore, since here the ENTITY statement for declaring the entity of the graphic file is stored as an ENTITY file having a file name same as the file name of the word processor document, to which the graphic file is added, into the graphic directory D 5 , for example, when editing, search for bugs or the like is performed for the hub document  100 , an entity declaration or the like regarding a desired attachment file can be searched out readily. Consequently, the operation efficiency is augmented and management of such files is facilitated. 
   Further, since the CPU  11  stores, after it converts all non-structured documents stored in the source directory D 3  into SGML documents, all of the thus prepared SGML documents as SGML documents of file names same as the file names of the non-structured documents into the sgml directory D 4 , for example, when editing, search for bugs or the like is performed for the hub document  100 , a desired SGML instance can be searched out readily. Consequently, the working efficiency is augmented and management after preparation of the hub document  100  is facilitated. 
   Furthermore, since an SGML document which combines a plurality of document instances can be prepared as the hub document  100 , the individual document instances can be prepared separately from one another and SGML documents can be prepared separately by a plurality of preparing persons, the efficiency in preparation of SGML documents is augmented. 
   It is to be noted that, while, in the embodiment described above, the hub document  100  is prepared in steps S 1  to S 4  in this order, the order in which steps S 1  to S 4  are to be executed is not limited to this, and they may be executed in any order. 
   The present invention is not limited to the embodiment specifically described above, and variations and modifications can be made without departing from the scope of the present invention. 
   For example, while, in the embodiment described above, an attachment file is a graphic file, it is not limited to this and may be any of sound files, program files and so forth. 
   Further, while, in the embodiment described above, the graphic directory director D 5  functions as the attachment file storage area  3  for storing an attachment file attached to a non-structured document and an entity declaration regarding the attachment file, it is not limited to this. For example, as seen from  FIG. 7  which illustrates a modification to the hub document preparation method of the present embodiment, an entity declaration storage area  4  for storing an entity declaration regarding an attachment file may be provided additionally while the attachment file attached to a non-structured document is stored in the attachment file storage area  3 . 
   More particularly, a graphic directory D 5  formed on the hard disk  12  is used as the attachment file storage area  3 , and further, a directory for storing an entity declaration regarding an attachment file is formed on the hard disk  12 . The newly prepared directory may be used as the entity declaration storage area  4 . 
   With the modification just described, similar effects to those of the embodiment described above can be achieved. Besides, since, upon preparation of a hub document, an entity declaration stored in the entity declaration storage area  4  can be extracted readily, a hub document can be prepared rapidly and readily, and the working burden to the preparing person is reduced and the working efficiency is augmented. 
   Further, in the embodiment described above, such a directory as the book 1  directory D 1  or the book 2  directory D 2  is formed for each SGML document to be prepared, and the source directory D 3 , sgml directory D 4  and graphic directory D 5  are formed in each of the book 1  directory D 1  and the book 2  directory D 2  such that documents of a format (non-structured documents) unique to a word processor before conversion are stored into the source directory D 3  and SGML documents (document instances) after conversion are stored into the sgml directory D 4  whereas copies of attachment files are stored into the graphic directory D 5 . However, the directory names and directory structures of the directories are not limited to them and may be determined arbitrarily. 
   Furthermore, while, in the embodiment described above, description is given only of a case wherein a structured document is an SGML document, it is not limited to this and may alternatively be an XML (Extended Markup Language) document.