VARIABLES

   $_       Default variable for operators to use
   $`       Everything prior to matched string
   $&       Entire matched string
   $'       Everything after to matched string
   $1,$2... Hold the Xth captured expr
   $+       Last parenthesized pattern match
   $^N      Holds the most recently closed capture
   $^R      Holds the result of the last (?{...}) expr
   @-       Offsets of starts of groups.
   @+       Offsets of ends of groups.