I see. In the BlenderBIM Add-on I have implemented it as the filename, devoid of the absolute path. e.g.
FILE_NAME('test.ifc',... I personally see very little utility in the absolute path, and especially less utility in Windows-style path separators which tend to make things a bit more annoying when later integrating it on a network. Therefore I don’t run into the Windows vs Unix style path separators.
I see that in ArchiCAD they have implemented a full path with Windows-style path separators, but unlike that PDF which gives
FILE_NAME('C:\IAI_Test_Building.ifc'... as an example, ArchiCAD escapes it, e.g.
FILE_NAME('D:\\00-Oficina\\10BIM\\ANALISIS IFC\\ARCHICAD 23_COLUMN.ifc'. This seems like a sensible solution, and points out a flaw in that PDF.
Revit ignores it altogether and goes pure STEP and just gives it the same value as the IfcProject Name attribute. E.g.
Ping @TLiebich who can perhaps verify what the original intent was? There seems to be a clear discrepancy in implementation.