This implies two capabilities:
- I can control what information other players can see about me.
- I can control how information about other characters is displayed to me.
So: From the point of view of other players, I want to be able to turn on or off any information about my character that isn't part of my personal appearance (body, clothing, gear, badges/rank insignia, etc.).
Suppose my character is wearing a Starfleet uniform in a Star Trek MMORPG. Based on what I've chosen for my character to display, you'd be able to determine the following information: "species = Human, faction = Starfleet, department = Tactical, rank = Commander." If I'm wearing my dress uniform, you could see "Human, Starfleet, Tactical, Commander, Grankite Order of Tactics, Palm Leaf of Gallospey Peace Mission."
But if I'm wearing civvies, you'd only be able to see my character's species and (if my species has such a thing) sex. There's nothing magically and inexplicably floating above my head, so you don't know my name, rank, serial number, or anything else. If you want to know those things, you'll need to talk to me and ask... unless I choose to turn on other information about me, such as my name, factional allegiance, rank, awards/badges/medals, biography, and so on, in which case you can have that information about me displayed to you in whatever way you like (more on that in a moment).
The reason for this approach is threefold. First, this information about me could serve a tactical purpose if PvP is ever enabled. The more you can learn about me before a fight, the better your odds of beating me. Therefore I ought to be able to control what information about me is available to other players.
Second, control over this information serves roleplaying. If I prefer that you should talk to me to learn my character's history, I shouldn't have that option taken away from me by having that "personal" info displayed without my consent.
And third, I believe that character customization is the next big battleground for MMORPG features. People want to have control over their personal information in games, just like many people do in real life. Respecting this desire as part of the game's design by giving players control over what information about their character is displayed would make a small but useful contribution to the overall satisfaction of players with the game environment.
So that's what I'm thinking about what information about my character is available to you. The other side of this coin is what power you have to determine how information about other characters is displayed to you.
Let's say I go into my character options screen and turn on all possible information about my character. You should then be able to go into you UI options screen and choose settings that determine what information about my character is displayed on your screen, and how it's displayed.
If you want to roleplay, you absolutely should be able to turn all that "floating" stuff off so that you have to click on someone's avatar to bring that information up. But if you're there to "win the game," then you should be able to turn on all kinds of information about other characters (if they've chosen to make that information available) -- their name, allegiance, rank, branch, guild/clan/fleet/crew membership, etc. And if there's a way to display that information other than as floating text, then you ought to be able to select those alternative presentation choices yourself.
Finally, I should reiterate that all this is information is innate stuff; these are things that aren't part of a character's "physical" appearance. If you put on some visible article of clothing or gear that is associated with a particular piece of personal information about your character (such as a uniform associated with a particular faction), then other players will know that information about you regardless of whether you've turned that bit of info on or off in your character information display options.
The point of all this is that players should, within reason, be able to customize their gameplay experience to their preferred playstyle. Giving players control over the management of information about characters -- their own and others -- would be a useful means to that end.
(Note: I emphasize "character-level" and "inside the game world" in my fundamental definition to distinguish such kinds of information from game-specific [usually numeric] information about characters that they wouldn't know themselves. If the characters would know it about themselves, then the gamer playing that character ought to be able to determine how it's presented or received inside the game world. But that should not be read as a justification for expecting the game to expose low-level internal game data about characters to their players that the characters wouldn't know about themselves.)