SNDLVL Enumeration doesn't exist in game

[Remscar]

Was looking around the wiki and saw reference to a SNDLVL enum: SNDLVL Enumerations
The enum is supposed to be used when emitting sounds, but it seems like the enum doesn't actually exist since running
print(SNDLVL_GUNFIRE) -- returns nill
Or any other arbitrary version of the SNDLVL_ enum returns nil

Is this intended behavior? If so, are the decimal values static across GMod versions and platforms?

[Rubat]

https://i.imgur.com/RQpD7Bp.png

Hmmmmmm

[NeatNit]

It seems clear that the decimal value is the decibels.