{}
{   This is the file access procedure (FAP) that processes requests for files
{ that are associated with a null device.
{   GET and PUT calls can be issued to a null file that has been opened for
{ record access.  The result of performing a GET on a file assigned to a null
{ device will be the return of normal status but no data.  The file position
{ returned after a GET call is always AMC$EOI.  Any PUT performed on such a
{ file will cause the data to be discarded and normal status is returned.  A
{ full record PUT call returns a file position of AMC$EOR; a partial record
{ PUT call to write the beginning or middle part of a record returns
{ AMC$MID_RECORD; a partial record PUT call to write the end of a record returns
{ AMC$EOR.
{   An AMP$GET_SEGMENT_POINTER call to a null file that was opened for segment
{ access returns a NIL pointer because the system does not assign a segment to
{ the file.
{}
{        BAP$NULL_DEVICE ( FILE_IDENTIFIER, CALL_BLOCK, LAYER_NUMBER,
{                          STATUS)
{}
{ FILE_IDENTIFIER: (input) This parameter specifies the file access
{       identifier established when the file was opened.
{}
{ CALL_BLOCK: (input) This parameter specifies the call block used
{       by this request.
{}
{ LAYER_NUMBER: (input) This parameter specifies the index into the
{       fap_control_information for this layer.
{}
{ STATUS: (output) This parameter specifies the request status.}
{}
