Bitmask-cvar

When you look into example.cfg (the one in the pk3) , you'll see this:

// b_demo_nametags - a bitmask controlling how floating names above each
// player are drawn during demo playback and when spectating as a shoutcaster.
// default: 0	valid values: 0-15
// add the following together:
// 1 = draw visible players
// 2 = draw all players
// 4 = draw the player's client number
// 8 = draw the player's class
set b_demo_nametags 0

This means that you can combine values!

Example #1:

You want to draw the nametag for all visible players AND the player's class must be drawn
1 = visible players
8 = player's class
8 + 1 = 9
set b_demo_nametags 9

Example #2:

If you want to see the clientnumber you have to add 4 to it
1 = visible players
4 = clientNumber
8 = player's class
1 + 4 + 8 = 13
set b_demo_nametags 13