Method for Cataloging Elements in a Computer Aided Design

Method for Cataloging Elements in a Computer Aided Design

      Disclosed is a method for cataloging and locating elements in a
Computer Aided Design (CAD) system using an external database.  A
non-graphic record attached to an element contains a unique key value
and a corresponding entry in the external database associates this
key with the file in which the element appears.  An application can
then use the external database to display a list of elements stored
in the CAD system, and display a selected element.

      Such a method involves the following main components.

1.  A CAD system that is extensible in that it provides a facility
    for application programs to be written on top of the basic system
    that can read and write records in the CAD database, and cause
    drawings to be displayed.  Additional capabilities such as
    control of the CAD user interface, and the ability to extend the
    command set of the CAD system allow further useful extensions of
    the CAD system and provide a more integrated feel to the method.

2.  A database system with a programmable interface accessible from
    the facility mentioned above.

3.  Authoring application program written on top of the CAD system.

4.  End-user application program written on top of the CAD system.

      The above components are used in the following manner:

o   Building the CAD database.
o   Authoring the element catalog
o   Using the element catalog.

BUILDING THE CAD DATABASE -  A collection of drawings (also called
Models in some systems) is defined either using the basic functions
of the CAD system, or by importing from other systems.  The result is
a CAD database containing many separate files each having a number of
graphic entities representing identifiable components (elements).

AUTHORING THE ELEMENT CATALOG -  Using the authoring application
program, the catalog of elements is built.  This process is comprised
of the following steps.

1.  Each drawing is displayed on the CAD system.

2.  For each drawing, all elements that will be of interest to the
    end-user are selected one at a time.  This may be a single
    element or a group of elements which would in turn be part of a
    pattern.

3.  A unique element identifier(ID) that will be meaningful to the
    end user is specified.

4.  A non-graphic record containing this ID and an application
    identifier that will be recognized by the cataloging application
    is attached to the element pattern in the CAD database.

5.  A record containing the ID and a drawing file identifier (usually
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