What conditional compilation symbols are available across each version of Unity?

Is there a full list of conditional compilation symbols available in any of the Unity documentation, or anywhere else?

Currently we are aware of the `UNITY_IPHONE` symbol, and there was one under Unity 2.5 as `UNITY_25`, however they don't appear to work in 2.6.1f3 now.

An interface to create custom defines would be ideal, however while this isn't available right now, a full list of what is there would be very helpful, as we are currently jumping between iPhone and Unity 2.6, and being able to co-develop them under a similar code base is goign to save us a lot of time.

The only built-in symbol I'm aware of is UNITY_IPHONE.

Regarding the interface, please support Editor: Interface for listing preprocessor macros (#define) in build settings by voting it up.

You may also be interested in Is there a way to have debug code compiled out for a final build? and What C# predefines are recognized by Unity?.

EDIT: According to the latter link, there should currently also be UNITY_2_6_1 - but as the version is included there, I wouldn't really on that and use UNITY_IPHONE instead (that's probably what broke UNITY_25 ;-) ).

Unity 3.0 has a more extensive list of preprocessor defines ... http://unity3d.com/support/documentation/Manual/Platform%20Dependent%20Compilation.html