I've seen a lot of players using abbreviations for the big ships (LNS-, OCV-, MNS-, etc.) and I would like to ask:
1. Do they have a relation with faction tags? Do the rules apply to that ones? I haven't seen something related to this, specifically.
2. Is this mandatory when I have characters with capital ships? or just recommended for roleplay purposes? From a point of view, they don't necessarily make sense with some civilian or unlawful ships because, in terms of roleplay, they could be operating with more flexible social/political/military structures that could permit this.
1. Yes, they typically show what faction they're a part of. LNS are Liberty Navy, MNS are Outcast, OCV are Order, etc. These are indie tags though, they still need to follow the server rules but they aren't a part of an official faction unless something like [LN] or 5th| precedes it
2. It's not mandatory in the slightest, I don't use it unless I'm in a faction that requires it. It's just become an unspoken guideline for people to follow. But it's fine to go without if you don't want to announce to the server that you're an Order cap sitting in Delta
Tags are intended to help people, by finding players in similar ships as themselves to help fight a threat. They are not mandatory. They do relate to factions and you should consider using the ones other people generally use, the ones you stated, but it is possible to make your own tag, but this is probably better when you make your own faction.