14.2.5 Virtual Files
  A virtual file is a random access file that stores one or
  more data records or virtual array elements in each physi-
  cal 512-byte disk block. You create a virtual file by specifying
  ORGANIZATION VIRTUAL as part of the OPEN statement.
  Apart from virtual arrays and compatibility with BASIC and
  BASIC-PLUS-2, you should use sequential fixed-length in-
  stead of virtual files, as they provide the same capabilities.
  See Section 14.5 for more information about accessing the
  individual records in a disk block.