isNumericFieldGroup determines if a field-group is a valid numeric field-group. (Private function.)
A numeric field-group is single, non-negative integer or a pair of non-negative integers separated by a hyphen.
Note that zero is valid by this definition, even though it is usually disallowed as a field number, except when representing the entire line.
See Implementation
isNumericFieldGroup determines if a field-group is a valid numeric field-group. (Private function.)
A numeric field-group is single, non-negative integer or a pair of non-negative integers separated by a hyphen.
Note that zero is valid by this definition, even though it is usually disallowed as a field number, except when representing the entire line.