2D Symbolic Representation

Draft allows design elements to be represented symbolically in a 2D View when the UPDATE Design command is executed. Symbolic representation may either replace or be in addition to the normal geometric representation of the elements.

Design symbols can consist of geometrical elements or text or can be a combination of both, including Draft Intelligent Text hash-codes. Design symbols can be scaled and oriented as required.

Graphic representation of design elements are controlled by Representation Rules; these are described in Representation Rules.

The 2D symbols are generated from templates stored in the Draft database. These are the Symbol Templates (SYTM) and the Text Label Templates (TXTM), used for generation of geometric elements or text elements, respectively. Refer to Basic Hierarchy for a diagram of the Draft database hierarchy.

The data defining which templates to use for a given design element, and under which circumstances, is stored in the Catalogue database. This allows several templates to be associated with a design element so that it can be represented differently in different types of Views. The representation of a light fitting, for example, could depend on both the View direction (that means, plan or elevation) and the View classification (for example, Room Design, Cabling, etc).

The design symbols are created as Design Symbol (DESSYM) database elements. DESSYM is a soft-type variant of the Special Label (SLAB) element. The DESSYM elements are added as members of a Design Symbol Layer (DSLAYE) element, which is a soft-type variant of the Layer (LAYE) element, and is therefore a member of a View. Only one occurrence of DSLAYE will be created per View during the UPDATE Design process, and the DSLAYE will be removed if it subsequently ceases to own any child DESSYMs.

From the above it can be seen that 2D symbols are created as part of the annotation of the View, rather than design graphics. DSLAYEs and DESSYMs are created and deleted automatically by Draft, with no user control over these operations.

DESSYMs will not be created for any design item whose origin falls outside the View rectangle or whose origin (or datum point) is excluded by the action of section planes.

Where only a symbolic representation is required (that means, when a normal geometric representation is not required in addition to design symbols), Draft will not attempt to determine whether the design items would have been hidden by the action of the Hidden Line Removal process.