I'd really like to have these two distinct values read from / stored to separate Document-specific values (non-static Field, in C#).
Never once, in my limited experience, have I ever needed to assign a Feature Line, or vertex elevation the same elevation as the Surface to which said Feature Line was ultimately to be applied as a breakline.
As a personal example:
When designing a proposed swale, I will cull the necessary elevation(s) from an existing Surface for the low point of said swale, yet apply the Feature Line that represents said swale to a proposed Surface.
It doesn't make any sense for the selected existing Surface from which to cull when assigning elevations, also be the default Surface to which one adds a breakline. Yes, I'm sure there's someone who can come up with a rare, but legitimate reason to do so, every leap year or three.
As a matter of frequency alone, I'd prefer to be able to have these be distinct (once assigned) for the majority of use cases, and allow user to choose the same Surface for those rare occasions, rather than always having to change them each-and-every-single time I need to perform one or the other operations.
Cheers
