The KEEP statement inserts a database key value from a currency indicator
  or keeplist into a keeplist.

  Format -

        [         [        { record-name } ]          ]
        [ CURRENT [ WITHIN { set-name    } ]          ]
        [         [        { realm-name  } ]          ]
   KEEP [ { OFFSET integer-exp }                      ]
        [ { FIRST              } WITHIN keeplist-name ]
        [ { LAST               }                      ]

      USING destination-keeplist

      [ ON ERROR stment ] [ NOT ON ERROR stment ]

      [ END-KEEP ]