Bearings are given in True (referencing True North) or Relative (from the bow).
Regarding AIS being given in relative (angle), if you are navigating at night or in the fog and the target stops reporting. You know the last report was 30°. Without looking for a compass reading, can you always tell me where 30°M is? I know you can tell me 30° relative. This is the reasoning behind AIS and Radar contacts being Relative.
I just went through all of this in the background with an error found regarding the EBL Line showing an "M" when it has nothing to do with Magnetic.
I hope this helps a bit. This topic comes up in cycles, and rightfully so. I can add this post to the wish list of product features.