7.2.4 Creating Arrays with the MAP Statement
  Create arrays with the MAP statement only when you want
  the array to be part of a record buffer, or when you want to
  overlay the storage containing the array. Note that string
  arrays in maps are always fixed-length.

  You associate the array with a record buffer by naming the
  map in the MAP clause of the OPEN statement.

  In the following example, the MAP statement creates two ar-
  rays: an 11-element fixed-length string array named team
  and a 33-element array of WORD integers named bowling_
  scores . Because the OPEN statement specifies MAP ABC , the
  storage for these arrays is used as the record buffer for the
  open file.
  MAP (ABC) STRING team(10) = 20, WORD bowling_scores(0 TO 32)
  OPEN "BOWLING.DAT" AS FILE #1%, SEQUENTIAL VARIABLE, MAP ABC