Windows ALT Codes, XML and FGU/FGC Compatibility
Throwing this out there as an FYI for all the other community devs and other interested parties.
To put it mildly, compatibility between modules built for both clients is going to a huge pain in the backside.
The ALT codes that the Classic client saves when you do a module export for the most part do not work in the Unity client, they are a Windows standard and NOT valid XML characters under any XML standard. The Classic client is extremely liberal in its application of the XML standards - and has been since before Doug and the gang took over.
Codes from 00 - 31 and 127-159 are control characters so don't function in Unity the same way as we expect them to in Classic. The two exceptions I have run across are the Line Feed (& #10;) and Carriage Return (& #13;).
Other character codes that you see in exported modules like & #133; & #146; & #147; & #148; & #150; and & #151; will display boxes as they are invalid in Unity's tighter application of the standard.
Fun times ahead... :D