If I have the core of a class defined in one file as "public partial" and I wish to create additions to this in another file, what is the difference between defining "public partial" again in my second file or just defining "partial"?
What happens if I define "private partial" in my second file?
You can duplicate the class modifiers or leave them out in one file, but you'll get a compiler error if they're specified in different files as different access levels.
From The C# Programming Guide:
The following keywords on a partial-type definition are optional, but if present on one partial-type definition, cannot conflict with the keywords specified on another partial definition for the same type:
- public
- private
- protected
- internal
- abstract
- sealed
- base class
- new modifier (nested parts)
- generic constraints