Features common to Eternity and ZDoom

To date, what are the features common between them? What features are planned to be commonly supported in the future? People have been repeatedly using the "crossport" keyword and it would be interesting to be elaborated. It sounds like a next-gen Boom after all. I know I was skeptical about it, but now I'm not.

Most MBF features are there...

For common features (other than those from Doom/Boom), a good starting point is to look here. It's the list of pages on the ZDoom wiki that for a reason or another link to the EE article.

You can also look at this. It's a test map with a few EE features that work in ZDoom.

You'll notice a difference in slopes, since they don't have any physics yet in EE.

Another good source of information would be 'xlat/eternity.txt' in zdoom.pk3. That file can tell you which Eternity line specials are supported by ZDoom.

Concerning portals, ZDoom does support the Eternity method of defining them but of course they are still limited by the same things as ZDoom's stacked sectors. (GZDoom can handle them better though.)