There's a difference between "target" and "modifier".
A target only has one endpoint. This is modeled by MakeTarget.
A modifier can have a max target and a min target, i.e it consists of two targets. In such a case it has a range of -1..+1, where 0 is that neither target is applied at all.
If you look in data/modifiers/modeling_modifiers.json (
https://bitbucket.org/MakeHuman/makehum ... ew-default), you can see that the modifier is specified with a base name and the suffixes for min and max. If you then look in the data/targets/nose for example (
https://bitbucket.org/MakeHuman/makehum ... at=default), you can see that there are ...-incr.target and ...-decr.target which specify the endpoints.