The new range control is defined with .custom-range class, but I wonder why it is CUSTOM.

The following is a list of bootstrap custom forms:

Why not .from-control-range or .form-range ?

Furthermore, I found .form-control-range class in the current SCSS:

but .form-control-range is not documented anywhere.
@mdo Any chance to treat the new range control as a standard or default rather than a custom, and change the class name to .from-control-range or .form-range?

Thanks.