Question Regarding Derived Works

[David Dillard]

Item #3 in the open source definition states that "The license must
allow modifications and derived works, and must allow them to be
distributed under the same terms as the license of the original
software."
 
Would a license that states that existing interfaces in the code cannot
be changed that violates this item?  After all new interfaces could be
added.
 
I think the issue boils down to this: does "allow modifications" mean
"allow any and all modifications" or "allow some modifications?"
 
 
I suspect that the spirit of the OSD is the former, but (to me) the text
says the latter.
 
 
--- David