Regarding the Mark 18 Mod 0 & "M4A1 CQBR" monikor
 

I recently came upon some info that leads me to believe that "M4 CQBR" might actually be the correct designation for certain 10" M4 variants. According to ArmyProperty.com, there are two different NSNs attached to the M4A1 CQBR upper (1005-01-498-1913) and Mark 18 (1005-01-527-2288). This suggests two different weapons. Some perusing on M4Carbine.net and AR15.com also revealed a couple of discussions highlighting that SEALs are issued a separate CQB upper along with their M4s, while the Mark 18 itself is a complete weapon system available for acquisition by units (e.g., Coast Guard, NCIS) requiring it.

http://www.armyproperty.com/nsn/1005-01-498-1913
http://www.armyproperty.com/nsn/1005-01-527-2288

Now obviously I'm not suggesting a separate entry on the M16 page for the M4A1 CQBR, since both the CQBR and Mark 18 are, by technical specification, the exact same weapon, but I am thinking that it might be prudent to add "M4A1 CQBR" to the approved list of names for 10" barreled M4 carbines for when dealing with movies/video games relating to SEALs, much like how we differentiate between the M21 and M25 designations for M14 sniper rifles on some pages.