Diagram object types

The graphical presentation of a diagram is built using the following kinds of objects.

• Diagram object types
• PD objects
• DG objects
• DW objects

PD objects

A PD object is an entity at the top of the P&ID diagram object hierarchy. It holds links to lower-level objects and to the external database.

Since diagram data is private to one diagram but the database is not, there can be a situation where several PD objects reference the same database card; for example, the same diesel motor is shown in several diagrams. Both these diagrams have independent PD objects which have a link to the same database card which holds information about the position ID, motor type, order number, and so on.

For more information, see PD object classes.

DG objects

DG objects are universal building blocks of a diagram. They store data about connections and links to graphics objects (DW).

For more information, see DG object classes.

DW objects

Only three DW object classes have any special meaning to the P&ID application:

• POLYLINE – The 2D line. These are inserted into a diagram as a result of inserting a new connection line (pipe run or instrument line).
• SYMBOL – The 2D symbol. Symbols are inserted into a diagram as a result of inserting a new DG symbol (diagram object).
• TEXT – Text is inserted into diagrams the same way as for POLYLINES and SYMBOLS.