C++ external client implementation

[AtomicBee]

Hi,
I've just joined this forum to learn/ask about this CAD editor.
I would like to create a simple C++ external COM client to manage CoCreate assemblies/particular.
What I want to do is something like:
1) open a CoCreate assembly;
2) write inside it some properties (string, int, double, date);
3) save the assembly;
4) close it;
5) open it again;
6) read the properties I've written at step #2;
7) save/export the assembly as PDF
8) close the assembly.

By reading the CoCreate.OsdmObjects.chm document (provided during the software installation) I have issues at step #3.
What object have I to use to save the current opened model/assy/particular?

I mean, both Document3D, Entity and Component classes have not a Save() or Export() member... what can I use?

T&R,
AB