Dimensioning to GRIDLN Elements

It is possible to dimension to GRIDLN elements. GRIDLN elements do not have ppoints but do have an origin position in the Design model, however this may well fall outside the VIEW boundary. To aid dimensioning to GRIDLNs the following special cases apply in Draft:

• Draft considers all GRIDLNs to be of infinite length.

• For all GRIDLNs Draft considers ppoint 0 to lie at their origins.

• For a GRIDLN that passes through a VIEW, Draft considers the 2 intersections that it will make with the VIEW boundary to be ppoints 1 and 2, and the mid-point between them to be ppoint 3. Dimension points (ie DPPTs) can be attached to these 'ppoints' (ie attribute NPPT). The default dimension point position (ie NPPT -1) is at P3.

• For a GRIDLN that does not pass through a VIEW ppoints 1, 2, and 3 are not defined. The default dimension point position (ie NPPT -1) is at P0.

It must be stressed that this concept of ppoints on GRIDLNs applies only in Draft. These ppoints only have World positions, their directions are not defined. Ppoint markers are generated by the Update Design process and can be identified by the 'IDP @' command in the normal fashion.