No units are implied by the value assigned to a variable. Variables simply contain numbers. As an example, if variable #1000 as we have defined it above were referenced in a part program after a (g) as we have done in the following line, it would refer to a coordinate system. In this case g55.
G#1000
If it were referenced after an (x, y, or z) it would refer to a positive distance on the named axis. That distance would depend on whether you had defined distance in inches or millimeters or some other unit.
X#1000
If #1000 were referenced after a (b) for a rotary axis it would refer to a positive rotation of 55 degrees. And if it were referenced after a (t) it would refer to a tool slot.
T#1000 M6
One consequence of the valuelesness of variables is that they will change meaning when you change from inches to millimeters in a program.