IFC Structure

Hello there

Are there any requirements that specify how the entries in an IFC (#1,#2,#3, etc.) should be listed?
Is such a random structure in an IFC file allowed? I have seen already files with a random order.


Many Thanks!

The order may be arbitrary.
(this is under IFC - STEP specification)

1 Like


From 11.2 in ISO 10303-21 (2016)

Each entity instance shall be represented at most once in the exchange structure and shall have an instance name that is unique within the exchange structure. The entity instances need not be ordered in the exchange structure. An instance name may be referenced before it is defined.

(emphasis mine)