Version management system

Abstract

A version management system for storing and retrieving changes to spreadsheet and word processor documents on a digital computer. The version management system is preferably integrated into the interface of existing spreadsheet or word processing software to permit a user to access a plurality of versions of spreadsheet or word processing documents. An original version of each document and all alternative versions are stored in a delta format, i.e., storing only the differences from a prior document version, in a common difference data file and version data file. A delta-formatted document will generally require less storage than an entire alternative version. Additionally, this delta formatting facilitates generating difference reports that emphasize the differences between multiple versions of a document. These difference reports are of particular value when applied to spreadsheet and word processing documents.

Claims

I claim:

1. A version management system for storing and retrieving user-selectable versions of a document maintained in a computer which has a displayer, comprising:

a user interface;

document processing software executable by the computer for driving said displayer to generate a display representing at least a portion of the document;

a first version control file for storing an original version of the document and at least one set of variable-sized delta-formatted data records representing differences between two user-selectable versions of the document;

a second version control file comprising at least one set of pointers for selecting a set of said delta-formatted records from said first version control file; said set of pointers corresponding to a user-selectable version of the document; and

a version management processor for fetching and processing said delta-formatted difference data to regenerate said user-selectable version of the document and supplying said regenerated user-selectable version of a document to said document processing software in accordance with selection by the user.

2. The system of claim 1, wherein said version management processor comprises a delta processor for applying said delta-formatted data records from said first version control file to said original version of the document to regenerate a second version of the document.

3. The system of claim 1, additionally comprising:

means for selecting a first and a second version of the document; and

means for formatting and displaying said first version of a document comprised of the plurality of display fields with a first of said display fields displaying document data in a first format where said document data is the same in said second version as in said first version and with a second of said display fields displaying document data in a modified format where said document data is different in said second version than in said first version.

4. The system of claim 3, wherein said modified format is selected from the group of bolding, font selection or color.

5. The system of claim 3, additionally comprising a configuration file for storing user-alterable data; wherein said modified format is selectable according to said user-alterable data.

6. The system of claim 1, wherein said document processing software is spreadsheet processing software and said original version document is a spreadsheet document.

7. The system of claim 6, wherein said spreadsheet processing software is selected from the group of Lotus 1-2-3, Microsoft Excel and Borland Quattro Pro.

8. The system of claim 7, additionally comprising formatting means to display said differences on said regenerated next document wherein unchanged data is represented with a value of 0.

9. The system of claim 1, wherein said document processing software is a word processing software and said original version document is a word processing document.

10. The system of claim 9, wherein said word processing software is selected from the group of Microsoft Word, WordPerfect and Lotus Ami Pro.

11. The system of claim 1, wherein said delta-formatted data records represent differences between two consecutive versions of the document.

12. The system of claim 1, wherein said delta-formatted data records represent differences between a user-selectable version of the document and said original version of the document.

13. The system of claim 1, wherein said second version control file additionally comprises data for identifying a version of the document.

14. The system of claim 1, wherein said user-selection means comprises means for selecting the document by identifying the document by a name and a version number.

15. The system of claim 14, wherein said document name and said version are selectable from a list of existing document versions.

16. A method for storing, retrieving and displaying a user-selectable version document maintained in a computer and supplying said version documents to document processing software, comprising the steps of:

1) identifying said user-selectable version document by a name and a version number;

2) retrieving an original version of said user-selectable version document document to form a first prior version document;

3) retrieving a set of variable-sized delta-formatted data representing difference data from said first prior version document;

4) applying said difference data to said first prior version document to regenerate a next prior version document;

5) repeating steps 3-4 for until said delta-formatted data representative of said user-selectable version document has been processed;

6) supplying said regenerated document to said document processing software; and

7) creating a display which includes at least a portion of said regenerated document.

17. The system of claim 16, wherein said document processing software is spreadsheet processing software and said documents are spreadsheet documents.

18. The system of claim 17, wherein said spreadsheet processing software is selected from the group of Lotus 1-2-3, Microsoft Excel and Borland Quattro Pro.

19. The system of claim 16, wherein said document processing software is a word processing software and said documents are word processing documents.

20. The system of claim 19, wherein said word processing software is selected from the group of Microsoft Word, WordPerfect and Lotus Ami Pro.

21. A method for storing, retrieving and displaying a user-selectable version document maintained in a computer and supplying said documents to document processing software, comprising the steps of:

1) identifying said user-selectable version document by a name and a version number;

2) retrieving an original version of said user-selectable version document;

3) retrieving a set of variable-sized delta-formatted data representing difference data from said original version document to said user-selectable version document;

4) applying said difference data to said original version document to regenerate said user-selectable version document;

5) supplying said regenerated document to said document processing software; and

6) operating said document processing software to create a display that displays at least part of said regenerated document.

22. The system of claim 21, wherein said document processing software is spreadsheet processing software and said documents are spreadsheet documents.

23. The system of claim 21, wherein said spreadsheet processing software is selected from the group of Lotus 1-2-3, Microsoft Excel and Borland Quattro Pro.

24. The system of claim 21, wherein said document processing software is word processing software and said documents are word processing documents.

25. The system of claim 24, wherein said word processing software is selected from the group of Microsoft Word, WordPerfect and Lotus Ami Pro.

26. A system for displaying the differences between two versions of a document each having a display format, comprising:

means for selecting a first and a second version of a document; and

means for formatting and displaying said first version of a document comprised of a plurality of display fields with a first of said display fields displaying said document data in a first format where said document data is the same in said second version as in said first version and with a second of said display fields displaying document data in a modified format where said document data is different in said second version than in said first version.

27. The system of claim 26, wherein said modified format is user-selectable from the group of bolding, font selection or color.

28. The system of claim 27, additional comprising a configuration file for storing data corresponding to said user-selectable modified format.

29. The system of claim 26, additionally comprising delta-formatting means for storing and fetching said first and second versions.

Description

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE INVENTION

The present invention relates generally to version management systems for spreadsheet and word processing documents and more particularly to systems for minimizing storage requirements by storing delta-formatted versions of such documents and systems that generate difference reports to facilitate comparisons between different versions of a document.

Common uses for computers, especially personal computers, include the processing of documents by spreadsheet processors, using programs such as Lotus 1-2-3, Microsoft Excel and Borland Quattro Pro, for displaying a tabular presentation of numerical data and word processors, using programs such as WordPerfect, Microsoft Word and Lotus Ami Pro, for generating and modifying primarily textual data. One of the major strengths of a computer is that its use allows a user to generate and evaluate modifications from original versions of documents. As part of this evaluation, a user or group of users may desire to compare different versions of these documents to determine an optimum result. Presently, this requires the storage of multiple versions of each document, which multiplies the data storage, i.e., disk storage, requirements of the computer. While disk storage capacity has vastly increased since the introduction of the IBM PC as well as the availability of disk compression software, it is still desirable to minimize disk storage requirements. Additionally, the known capabilities for comparing documents is limited. For example, Microsoft Excel is known to be able to generate a list of differences by cell addresses but fails to show version comparisons within its normal spreadsheet display format.

SUMMARY OF THE INVENTION

The present invention is directed toward a version management system, applicable for maintaining a plurality of versions of spreadsheet or word processing documents, for operation on a digital computing system, e.g., a personal computer (PC). Embodiments of the present invention preferably include delta-formatting means for storing subsequent versions of each document such that only changes from each prior version are stored.

A version management system in accordance with the invention preferably includes a version management processor operating in combination with a document processor for storing and retrieving a plurality of documents stored in a digital computer. An original version of a document is stored in a common file with subsequent versions of the document as delta-formatted data representative of the differences from a each prior version document.

In a preferred embodiment of the present invention, all of said delta-formatted document versions are stored in a pair of commonly used files where a first file contains said delta-formatted data pertaining to differences from a prior version of a document and a second file contains identification data and pointers for selecting delta-formatted data from within the first file to be applied to generate a desired document version.

Embodiments of the present invention preferably include means to format documents to emphasize changes between versions. In one mode, only difference data is displayed and any unaltered data, such as in a spreadsheet, is displayed with a value of 0. Alternatively, the altered data is formatted according to user-selectable options to emphasize the changes via bolding, font selection or color.

In a preferred embodiment, sets of delta-formatted data are consecutively applied to regenerate intermediate files until a desired version is regenerated. In an alternative embodiment, the delta-formatted data is directly applied to the original version of a document.

Embodiments of the present invention preferably include version management processors for interfacing to spreadsheet processors, e.g., Lotus 1-2-3, Microsoft Excel and Borland Quattro Pro, and word processors, e.g., Microsoft Word, WordPerfect and Lotus Ami Pro.

Other features and advantages of the present invention should become apparent from the following description of the presently-preferred embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 comprises a typical prior art spreadsheet processing system;

FIG. 2 comprises a functional block diagram of a version management system in accordance with the present invention as applied to spreadsheet processing;

FIG. 3 comprises a simplified block diagram of the structure of version control files comprising a version file and a delta-formatted difference file;

FIG. 4 comprises a simplified block diagram of the check-in, check-out procedure to the library directory;

FIG. 5 comprises a simplified block diagram of the structure of a project area;

FIG. 6 comprises a simplified block diagram of the structure of a project group;

FIG. 7 comprises a representation of the menu for a preferred embodiment;

FIG. 8 comprises a block diagram of the functions available from the menu in FIG. 7;

FIGS. 9-14 comprise representations of various dialogue boxes accessible from the menu of FIG. 7;

FIGS. 15-16 comprise displays representative of two versions of a spreadsheet document as normally displayed by a spreadsheet processor;

FIGS. 17A-17C comprise alternative representations of difference data displays available from a preferred embodiment;

FIGS. 18-21 comprise additional representations of various dialogue boxes accessible from the menu of FIG. 7; and

FIG. 22 shows a block diagram of top level implementation for a user interface.

FIG. 23 shows a block diagram of an initialization sequence for the user interface.

FIG. 24 shows a block diagram for an initialization menu for a user interface.

FIG. 25 shows a block diagram for a menu with selection and action blocks for a user interface.

FIG. 26 shows a block diagram of an exit sequence for a user interface.

FIG. 27 shows a block diagram for an open dialog for a user interface.

FIG. 28 shows a block diagram for an open dialog initialization for a user interface.

FIG. 29 shows a block diagram of a save dialog for a user interface.

FIG. 30 shows a block diagram of a save dialog initialization for a user interface.

FIG. 31 shows a block diagram for a save as dialog for a user interface.

FIG. 32 shows a block diagram for a save as dialog initialization for user interface.

FIG. 33 shows a block diagram for a move-copy dialog for a user interface.

FIG. 34 shows a block diagram for a move-copy dialog initialization for user interface.

FIG. 35 shows a block diagram of a delete ›file! dialog for a user interface.

FIG. 36 shows a block diagram for a delete dialog initialization for a user interface.

FIG. 37 shows a block diagram of a compare dialog for a user interface.

FIG. 38 shows a block diagram of a compare dialog initialization for a user interface.

FIG. 39 shows a block diagram of a compare setup dialog for a user interface.

FIG. 40 shows a block diagram for a compare setup dialog initial for a user interface.

FIG. 41 shows a block diagram of a project created dialog for a user interface.

FIG. 42 shows a block diagram of a project create dialog initialization for a user interface.

FIG. 43 shows a block diagram of a project delete dialog for a user interface.

FIG. 44 shows a block diagram for a project delete dialog initialization for a user interface.

FIG. 45 shows a block diagram of a check out processing.

FIG. 46 shows a block diagram for a check-in processing.

FIG. 47 shows a block diagram of project-file-version lists.

FIG. 48 shows a block diagram for project-file-version lists.

FIG. 49 shows a block diagram of project-file-version lists.

FIG. 50 shows a block diagram for an initialization dialog box database.

FIG. 51 shows a block diagram for a spreadsheet comparison report.

FIG. 52 shows a block diagram for a CCC-file setup dialog for a user interface.

FIG. 53 shows a block diagram for a CCC-file setup dialog initialization for a user interface.

FIG. 54 shows a block diagram of a module name: Diff2items.

FIG. 55 shows a block diagram of module name: Generate delta.

FIG. 56 shows a block diagram of module name: Build line vector of desired version.

FIG. 57 shows a block diagram of module name: deMergeitem.

FIG. 58 shows a block diagram of module name: deListchangeitem.

FIG. 59 shows a block diagram of module name: deListdiffitem.

FIG. 60 shows a block diagram of module name: deDeleteChangeitem.

FIG. 61 shows a block diagram of module name: deScantextitem.

FIG. 62 shows a block diagram of module name: deCheckoutitem.

FIG. 63 shows a block diagram of module name: deCheckinItem.

FIG. 64 shows a block diagram of module name: Delta Engine Component.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the following detailed description, similar reference characters refer to similar elements in all figures of the drawings.

With reference now to the drawings, and particularly to FIG. 1, there is shown a block diagram of a typical prior art system 10 that can process a plurality of different versions of a document. An exemplary system for processing spreadsheets is now described. However, it should be recognized that word processing systems operate in a similar manner. Typically, processing systems are comprised of a personal computer (PC) 12 having a nonvolatile storage device 14 such as a hard disk and a processing subsystem 16 that includes a digital processor 18 and a volatile storage 20 device such as a RAM. Spreadsheet software 22 is stored within the nonvolatile storage 14 where it is fetched by the processing subsystem 16 and loaded into the volatile storage 20 for execution by the digital processor 18. The digital processor 18, under control of a spreadsheet processor 24 (which is essentially a copy of the spreadsheet software 22 in volatile storage 20), can be controlled by a user to retrieve one of a plurality of versions of documents 26, 28 or 30, stored as files in the nonvolatile storage 14. In such systems, each version 26, 28 and 30 is a stand-alone document, that is, each document can be retrieved by the processing subsystem 16 without any reference to a prior version. This technique ignores the potential commonalities between versions and thus much of the contents of the nonvolatile storage 14 is potentially redundant on prior versions of documents. Thus, in particular for a spreadsheet document where only cell data has been modified between versions, the file size of each version of a document will be essentially identical.

With reference now to FIG. 2, there is shown a preferred embodiment of a version management system 32 that minimizes the storage requirements from the prior art and additionally provides improved means for comparing different document versions. In a manner similar to the prior art, the PC 12 is still comprised of nonvolatile storage 14, a processing subsystem 16, spreadsheet software 22 that is loaded into volatile storage 20 in the processing subsystem 16 for processing documents under control of the spreadsheet processor 24. However, preferred embodiments of the present invention additionally comprise version manager software 34. The version management software 34 and the spreadsheet software 22 are loaded into the volatile storage 20 in the processing subsystem 16 to form a version manager processor 36. The version manager processor 36 serves as an interface between the spreadsheet processor 24 and information stored in a library directory 38. The information in the library directory 38 includes a pair of version control files (a version data file 40 and a difference data file 42) corresponding to all existing document versions (Versions 1-N), all stored in the nonvolatile storage 14. The version manager processor 36 additionally comprises a delta processor 44 that stores and retrieves each version of a document in reference to each prior version using the version control data files 40 and 42.

When versions are retrieved from the library directory 38, this operation is referred to as checking out a document. Similarly, when a subsequent version is stored in the library directory 38, this operation is referred to as checking in a document. Each version of a document is stored as a set of variable-sized delta-formatted data records representing characters, words, lines, paragraphs, or any other elementary portion of a document. Initially, when Version 1 of a document is checked out from the library directory 38, the Version manager processor 36 recognizes this document as an original version and thus transfers this document, essentially unchanged, as a current version 46 to a working directory 48 where it is accessible to the spreadsheet processor 24. One may regard Version 1 of a document as a single delta-formatted record showing the differences from a void document, thus it may be used in its entirety without significant processing. However, if Version 2 of a document is checked out from the library directory 38, the version manager processor 36 recognizes this as a subsequent version. The version manager processor 36 will first retrieve Version 1 of the document from the common version control data files 40 and 42 and then fetch the set of data records pertaining to Version 2 from the version control data files 40 and 42 and use their contents to modify the data previously retrieved from Version 1 of the document. The spreadsheet processor 24 drives a displayer 50 to generate a display 52. The displayer 50 is usually a video monitor and/or a printer and the display 52 is a video screen and/or a printed page.

Since the version control data files 40 and 42 contain only difference or delta data from each prior version document, this data is referred to as being delta formatted. Document versions saved in a delta format generally require less disk space than the original documents. Similarly, if Version 3 of a document is checked out from the library directory 38, the version manager processor 36 will first fetch Version 1 of the document from the version control data files 40 and 42 to generate the original document and then fetch data records pertaining to Version 2 of the document from the version control data files 40 and 42. The version manager will then use the delta processor 44 to apply the delta-formatted data contained within the version control data files 40 and 42 to regenerate an intermediate Version 2 document. The version manager processor 36 will then process the delta-formatted data from version control data files 40 and 42 pertaining to Version 3, and the delta processor 44 will apply this delta-formatted data to the intermediate Version 2 document that was just regenerated, to regenerate the Version 3 document. This regenerated Version 3 document is then stored as the current version 46 for processing by the spreadsheet processor 24. This process can similarly iteratively repeat for Version N of a document. Embodiments of the present invention preferably support versions and subversions of a document and thus limit the number of regeneration iterations required. Thus, a Version 2.1.1 of a document is regenerated from Version 1 of a document and a regenerated Version 2 document but will not require regenerating Version 3 of a document. This concept, referred to as branching, is described further below. In an alternative embodiment, the delta-formatted data within the version control data files 40 and 42 can directly reflect Version N changes from Version 1, the original version, of a document 26 without referencing any intermediate delta-formatted data and thus without generating any intermediate versions, e.g., Version 2, Version 3, etc.

FIG. 3 shows the basic structure of the version control data files 40 and 42. The difference data file 42 contains sets of data records reflecting the delta-formatted differences from each prior version of a document, e.g., the changed data and the cell location in a spreadsheet. The first set of data records pertains to Version 1 of a document, that is the original unmodified document. Since this is the first version it reflects the differences from a void document and thus contains Version 1 of the document essentially intact. One or more records exist for each document version. Thus, the difference data file can contain a large number of data records since there can be a large number of versions and changes peculiar to each version. If a system required access to each data record to determine its relevance for a particular version, the performance of such a system would be degraded. Thus, the version data file 40 preferably contains a set of pointers 54 for each stored document version that point to a set of data records in the difference data file 42 that are used to regenerate each document version. By using the set of pointers 54 from the version data file 40, a significant speed improvement is accomplished.

In addition to the pointer data 54, the version data file 40 additionally stores identification data 56 for providing attributes to each version changed from the prior version. The identification data 56 preferably identifies the date and time the version was created, a version name associated with the version, text describing the reason for the change, and the user making the change. When a new document is saved, i.e., checked in, to the library directory the version manager processor generates the version data file 40 and the difference file 42 for the new document. When each subsequent version is checked in to the library directory 38, the version manager processor 36 using the delta processor 44 updates and stores the version data file 40 and the difference data file 42 to reflect the changes in the subsequent version.

As a consequence of the previously-described delta-formatted storage method, embodiments of the present invention can generate data adapted to display the differences between any two selected document versions. For example, the set of delta-formatted data for a particular version preferably contains data that directly represents the difference between two consecutive versions of the document. Normally, a regenerated version file is displayed as a plurality of display fields, each having a character display format inherent to each display field. Instead of displaying the regenerated version document according to its inherent character display format, the user can direct the version manager processor 36 to alter the character display format for display fields which reflect differences between selected document versions. The method used to display this data is determined by the user and stored within a configuration file 58 (FIG. 2) retained in the nonvolatile storage 14. In a preferred embodiment, these differences can be displayed through any combination of bolding, font type, or changes in color of display.

A preferred embodiment of the present invention is currently under development by the assignee of the present invention. In this embodiment, shown in the following pages, a version management system adapted for a Microsoft Excel spreadsheet processing system operating under Microsoft Windows is described. It should be apparent to one of ordinary skill in the art that the teachings of this application are equally applicable to other spreadsheet processors and word processors operating on a PC or any computing system. The following comprises a Product Description that includes a description of different parts of software in processing data, and a User Interface Description that includes features that can be selected by a user. With this embodiment, a user identifies a document by its name and by an available version number, preferably from a list of available documents and associated versions. These two choices are provided to the version manager processor 36 that uses the previously described process to regenerate the selected document version.

1. Product Description

The spreadsheet version control processor 36 stores document versions in an independent library directory 38, as defined by the user. Alternative versions of a document will be stored in delta file format, thus minimizing storage space. Stored versions can be retrieved at any time, worked on, saved in a working directory, and then checked back into the library structure as a new version. If a document version before the "latest" version is checked out, the user can save it as the "latest" or "interim" (branch) version.

1.1 Software Execution

This product will be installed so that it will automatically execute whenever the host application is initiated, where the host application is defined as the spreadsheet application using version control. Additional menu selections will provide access to all software functionality.

1.2 Data Storage & Retrieval

This product will store all of its data in the library directory 38 on a hard disk, which is designated by the user. With reference to FIG. 4, a file is checked out and locked from the library directory, and copied to the working directory 48. While the file is being updated, it can be saved using the File-Save option from the main menu, and it will be stored in the working directory 48 during this period. When final modifications are saved to the working directory 48, the user can then perform a Version Save which will be an option provided in this product's main menu. At this point, the file will be automatically saved again to the working directory 48. It is then copied to the library directory 38. While a copy of the file will remain in the working directory 48, it will have the read-only attribute switched on so that modifications cannot be made to it without performing a check-out from the library 38.

Data storage will be performed by creating directory structures to separate project areas. Each project will further be divided into sub-directories as needed by the software. There will be a base library directory. In the base library directory, project sub-directories will be created--one to each project. As project names can be more than 8 characters long, a database file will be written to the library directory which will map each project name to a given project directory. (The maximum length of a project name is 40 characters.)

Within each project directory, there will be two sub-directories--one is d and the other is v where d is for storing the difference data files 42 and v is for storing the version data files 40. A sample directory tree is shown in FIG. 5. In this example, cfilelib is the base library directory. Revenue, bookings, and forecast are project sub-directories that represent various areas, such as would be used by an accountant. In each of these subdirectories exists additional sub-directories known as d and v, as described above.

The current status of each given document is maintained in its respective version data file 40 within sub-directory v. This will be accomplished in the file header. As for information that goes along with each version, data strings will be inserted in each version's records in the version data file 40. This will include the name of the version, the person who changed it and the change comment. (Other information, such as date & time and version number are already stored in this file.) The file header will hold information about whether a document is checked in, checked out, read/write status and the version that is checked out.

1.3 Version Numbering

For library check-ins, this product will create a new version number automatically. The baseline copy of a given document will be version number 1. Its revisions would then be versions 2, 3, 4, and so on. Branched versions are numbered 1.1.1, 3.2.2, 5.1.2.3.2, 3.10.23.1.2, or some combination fitting this pattern. Periods are used as branching level separators. Also, each version number will be required to have an odd number of numbers. Thus, 1, 1.1.1, 1.1.1.1.1, and 1.1.1.1.1.1.1 are valid version numbers, and 1.1, 2.2.2.2, and 3.3.3.3.3.3 are invalid version numbers.

1.4 Branching

Branching will be utilized on demand by the user. Under normal conditions, versions of a document will be designated by single-level version numbers. If the stored versions are 1, 2, and 3, and version 3 is the latest version and versions 1 or 2 are checked out, the newly-created version will be version 4. Branching can be manually selected by the user at save. In this specific case, a check-out of version 2 and then a check-in with branching will yield version 2.1.1. Checking in a new version 2.1.1 will yield version 2.1.2. The branch of version 2.1.1 would be version 2.1.1.1.1. Up to five (5) branching levels will be allowed (i.e., Version 1.2.1.1.1 has the maximum number of parts available) in the display, although the software itself allows for more branching levels. A sample tree with branches is as follows:

    ______________________________________
                  1.1.1
                         1.1.1.1.1
                         1.1.1.1.2
                  1.2.1
                  1.2.2
                         1.2.2.1.1
                  1.1.2
                  1.1.3
    2
    3
    ______________________________________

• Inventors
  Hug, Richard A.; Presser, Leon;
• Assignee
  Softool Corporation (Goleta, CA)
• Published
  Sep-8-1998
• Current US Classes:
  707/203
  715/511
• Application #
  257816
• International Classes
  G06F 015/00
• Field of Search
  364/419.19 364/225.3 364/225.4 364/225.6 364/966 364/400 364/401 364/402 395/600 395/772 395/765 395/779 395/619 395/712 395/326 707/200 707/203 707/511
• Examiner
  Hayes; Gail O.
• Agent
  Wilson Sonsini Goodrich & Rosati
• US Patent References:
  4809170
  5231577
  5303146