^\s*    #start/optional spaces
1?(\.|\-)?\s*           #an optional 1- or 1. with optional spaces
(
(\(|\[|\{)?             #an optional bracket ( or { or [
\s*(\.|\-)?\s*         #space or optional . or -
\d\s*(\.|\-)?\s*      #digit optional . or - and spaces
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
(\)|\]\})?               # choice of closing brackets
)?                          # that section was optional
\s*(\.|\-)?\s*   #space or optional . or -
\d\s*(\.|\-)?\s*      #digit optional . or - and spaces
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
\d\s*(\.|\-)?\s*      # ditto
$                          # nothing more allowed