From Quake Wiki
A floating point value.
Floats are also used to store booleans (TRUE, FALSE) or integer values linke counters, or bit flags.
Valid syntax: 12, 1.6, 0.5, -100 Invalid syntax: .5
A parsing ambiguity is present with negative constants. "a-5" will be parsed as "a", then "-5", causing an error. Separate the - from the digits with a space "a - 5" to get the proper behavior.