# Assign a name to surface in CAD STEP file

I have a CAD model designed in FreeCAD and need to export it to a STEP file (neutral CAD format) to be used in numerical anaysis software. I would like to assign names to selected surfaces in order to later define analysis boundary conditions on them. Is there a way to

• Define surface names directly in FreeCAD so that they are kept by the STEP export and seen by the analysis pre-processor after import, or
• Manually edit the STEP file and inject the names at approproiate places

Regarding the second option, I am able to identify the relevant surface and the definition looks like this

#885 = CYLINDRICAL_SURFACE('',#886,53.);


I tried adding a name between the apostrophes but this didn't seem to make any difference

#885 = CYLINDRICAL_SURFACE('mySurfaceName',#886,53.);


A link to a detailed description of the STEP format would be very useful too.

• have you discovered that if you search for "detailed description of the STEP format" it will return many links for this information? – fred_dot_u Jan 23 at 15:02
• I'm looking for a command reference describing what arguments each command takes, e.g. CYLINDRICAL_SURFACE(arg1, arg2, arg3). The STEP format is complex and reverse engineering is very difficult. I haven't found any such reference. – FliegenderZirkus Jan 24 at 12:24