This tagging discussion is relevant for PR703 so I added a copy of this email there.
EBICAB is a trademark for on-board equipment, from a specific supplier (Bombardier). The entire train protection system contains some other things . The entire system is called ATC in Norway and Sweden, while Portugal calls the exact same system CONVEL. To add more confusion: Denmark calls [its own system](https://de.wikipedia.org/w/index.php?title=ZUB_123) ATC , while it is incompatible with the Norse/Swedish/Portuguese system.
Also the current situation in OSM is different than you currently envision (with adding the `railway:ebicab=700` tag): in the past I already added `railway:atc=yes` tags to relevant tracks in both Portugal and Norway with the same purpose. You also envision the `railway:ebicab=900` tag (probably for Finland) while Finland uses the `railway:jkv=yes` tag with the same purpose. Denmark is a bit of a blank slate, because Denmark doesn't have train protection tags yet.
OpenRailwayMap has 2 options:
1. Render compatible systems
a) we proceed with this PR as is
b) we have to retag Portugal, Sweden, Norway and Finland (I'm willing to help)
c) we should create an additional PR to also render `railway:zub=123`
d) Denmark should be tagged with `railway:zub=123`
2. Render local names
a) this PR should change to `railway:convel=yes`
b) we should retag portugal from `railway:ebicab=700`/`railway:atc=yes` to `railway:convel=yes`
c) we need an additional PR to render `railway:atc=yes`
c) Denmark should be tagged with `railway:atc=yes`
I am in favor of option 1, because my opinion is that the goal of ORM signalling layer should be to show compatibility.
 Overview of train protection systems in PT, DK, NO, SE, FI as far as I currently understand them
 Danish border, seen from Germany. Note the start-of-ATC signs.