Need help understanding STEP import and export prefs

Post by **Roy_043** » Sun Feb 23, 2020 7:54 pm

I am working on this wiki page:
https://www.freecadweb.org/wiki/Import_ ... Preference

I want to add the new V0.19 STEP import and export options, but have a hard time understanding them. And a WWW search doesn't give me any useful links.

STEP export options

Export invisible objects: I think I sort of understand how this works but find it strange that invisible objects are not exported as invisible.
Export single object placement: I don't understand this option.
Use legacy exporter: I need some info about the difference between the current and the legacy exporter.

STEP import options:

Use LinkGroup: When checked assemblies are imported as a single compound?
Import invisible objects: Seems an obvious option. But I can't create a STEP with invisible objects in FreeCAD.
Reduce number of objects: I don't understand this option.
Expand compound shape: I don't understand this option.
Show progress bar when importing: This is pretty obvious. But why is this not the default behavior?
Ignore instance names: I don't understand this option.
Mode: I think I understand this.