The IfcDimensionCount defines the dimensionality of the coordinate space. It is restricted to have the dimensionality of either 1, 2, or 3 for the purpose of this specification.
8.9.2.7.2 Formal Propositions
WR1
<html><body><p>The dimension count should be an integer between 1 and 3 NOTE: This is a further constraint by IFC, the upper limit does not exist in STEP.</p></body></html>