[Black Wolf]

What about a "SCP Enabled" mission flag? This could be put into FRED so that everything you don't turn on via sexps (eg. any potential future AI enhancements, Tertiary weapons etc.) is activated. If you don't check it (ie. If it's a mission made Pre SCP, Including the [V] missions) nothing changes. Also, since so far nobody's done anything that'd break backwards compatibility, you'd not need to modify any old code, just add new stuff to any future changes. So, possible?

[JarC]

I'm with you on the idea of such a flag, buth I'm a bit sceptic with the second part of your suggestion, automatically turning on stuff.
As long as there's a way to shut it off again some way than I think it would be a good idea, but not if that takes away control over something away from the missiondesigner...I don't know if there even is a sexp for every new feature to do this, could just be that since you need to explicitly turn it on and it being off by default, has negated the introduction of such toggle-sexp's for every feature...

[Black Wolf]

Well, yes, there'd have to be some toggles and stuff. I didn;t word it very well I guess. The basic idea is just to give the coders the ability to put in stuff that will break backwards compatibility by making a mission flag that activates it. ie. without it, none of the changes come into effect, nor does it even look for the changed stuff. Allowing older misisons to work without breaking anything in a new FSO.

[Goober5000]

If coders put in stuff that breaks backwards compatibility, they're not doing their job right.  Our principle is to make all the new features compatible with the old ones and off by default.

All additions are activated on a per-feature basis anyhow.  We can't add a flag like this because there's no support to activate "all features except X".

So the answer is a solid no.  Sorry.