Symbol Entity Creation Rules

For performance reasons, avoid as much as possible the use of nested blocks with the exception of the symbol ports. Explode the AutoCAD entity while creating P&ID symbol if it consists a block in it.

Colour of the entities use in the creation of symbols should be set to "byblock", ensuring colour inheritance rules implemented in the application will work as expected.

Layers of all entities should be set to "0".

Linetypes should be set to "byblock".

Symbol port layers must be set to layer defined against item type POR.

Avoid complex entities such as hatch patterns, dimensions.

Use entities generated by commands like "DONUT" or "SOLID" to create solid areas.

The user must insert ports to define connection points, connection ports and symbol insertion points (base points) must be aligned:

The user can add behaviour such as automatic symbol flipping based on flow direction by naming one of the ports to "20":

Symbols like this (for example, a check valve), as shown in above picture, will flip in the correct direction (or not) depending on the graphical creation and the position of the port set to "20".

Other symbols with special behaviour are reducers. For reducers, ports should be named as 1 and 2. The location of the ports depends on the graphical creation of the symbol.