Currently I'm connecting an Inventor Face on a Part Document.
Applying some material and connecting to a DB.
I'm using the internal name as identifier, but I don't know if its persistent the internalname.
And if the Surfacebody change what would happen to the parts.
Also is there another way to identify a Face element on a part document.
Thanks for the help
The Face.InternalName is persistent until it is destroied.
Another way to retrieve a Face is to use the ReferenceKey, use the Face.GetReferenceKey and ReferenceKeyManager.KeyToString to store the ReferenceKey of a Face, then when you want to retrieve the Face use the ReferenceKeyManager.StringToKey and BindKeyToObject.
As Rocky mentioned, ReferenceKeys is the way to go to identify reliably faces.
You can take a look in the APi Help Files which have a dedicated topic and the Inventor Training Material (Module 18), for samples in C# and Vb.Net.
Hope that helps,
Philippe.