In Norway the IFC-format is approved as a national archive format for BIM-models.
This approval leads to requirement for a strict format versioning regime.
For a typical IFC-file the format version is given like this (from Archicad):
But we need to know if it is IFC 4.0.2.1, IFC 4.1.0.0, IFC 4.2.0.0 or IFC 4.3.rc.1 e.g.
Is the requirement for writing the FULL format version into the IFC-file missing in the IFC-standard or is it just neglected by the software vendors?
I have seen a list of schema identifiers in IfcOpenShell: https://github.com/IfcOpenShell/IfcOpenShell/blob/f01ae4a45b3fc294ab5bcd4de494cc446ac587dc/cmake/CMakeLists.txt#L462
set(SCHEMA_VERSIONS "2x3" "4" "4x1" "4x2" "4x3_rc1")
I don’t know if they are official buildingSMART ones, or specific to IfcOpenShell.
If buildingSMART does indeed have a list of official identifiers, then indeed, perhaps the vendors are just neglecting them or are unaware 
Would be interested to know the answer too!