Hi Marc
File -> File Special -> IFC 2x3 -> IFC Scheme Setup
is where you start...
Beyond that I get a little lost, but if you find the subtype that works for your object you can then create rules to write GDL Object Parameters to IFC Attributes. I've found the BuildingElement Proxy one usually works for me (for objects, it's different for windows/doors/zones ect)
Couple of things to be wary of, hidden parameters can't be mapped (that hidden with the X in the parameter list, but parameters hidden with HIDEPARAMETERS can) and also you parameter must have a name in the parameter lis to be mapped. Took me a while to realise those two
.
Good luck.
AC 24 5004 AUS
iMac OSX (10.13.6) 4.2ghz i7
8gb ram/8gb vram