CODEWITHSUNDEEP
ifc
Extrakun
Extrakun

Reputation: 19325

What is the meaning of $ in a IFC definition?

This is a snippet of IFC definition:

#20=IFCORGANIZATION('','Anon Consulting','',$,$);

What are the meaning of the $ characters? For now, my educated guess is that they represent `null. Where can I verify this?

Upvotes: 2

Views: 646

Answers (2)

FlixFix
FlixFix

Reputation: 63

The '$' sign stands for a value that is infinite. For example within the entity, IfcTransitionCurveSegment2D, if it is an entering transition the radius is usually infinite. If you look at the STEP file it will have a '$' sign instead of an infinite sign or similar.

Further some properties within the ifc entities are optional, meaning you don't have to define them in order to create a valid ifc object. Whenever an object has an optional property, which is not defined by the user, the program aso, it will show as a '$' sign too within the STEP.

All this is documented in the ISO 10303 -21 if you wanna look into this any further. I hope I could help.

Upvotes: 1

Andy Ward
Andy Ward

Reputation: 369

BuildingSmart (owner of the IFC standard) says

The $ character encodes the indefinite value, i.e. it appears if an optional attribute has not been filled in.

So, yes, it is essentially a 'null' value.

Source: http://www.buildingsmart-tech.org/implementation/faq/faq-specific-ifc-spec#Q6

Upvotes: 6

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