$input =~ /^
            (?:                 # Non-capturing parens
               [^_]             # All non-underscores
               |                # or
               _                # underscore
               (?!              # not followed by
                 ${value}       # the current standards
               )
            )+                  # 1 or more characters like above
            _${value},          # Current standard followed by comma
            (                   # Capture to $1
              (?:               # Non-capturing parens
                 [A-Z]\d{1,2},? # One cap, one or two digits, and an optional comma
              )+                # Above one or more times
            )                   # End capture
            .*                  # Rest of line (okay to be greedy here)
         /ix;