{
{   The purpose  of  this procedure is to locate an unused entry in the member
{ vsn list of a master volume set table.   The  master  volume  set  table  is
{ assumed  open  prior  to  this request, and a pointer to the member vsn list
{ must have been constructed.  If an unused entry is found the  index  to  the
{ entry is returned.
{
{       STP$SEARCH_MVL_FOR_UNUSED_ENTRY (P_MEMBER_VSN_LIST, MVL_INDEX,
{         UNUSED_ENTRY_FOUND)
{
{ P_MEMEBER_VSN_LIST: (input) This parameter specifies a pointer to the member
{       vsn  list  in  the  master  volume  set  table (device file).  If this
{       pointer is NIL, unused_entry_found is returned as FALSE, and no action
{       is  taken.   If  this  pointer  is  not NIL its value is assumed to be
{       legal.
{
{ MVL_INDEX: (output) IF unused_entry_found = TRUE this returns the  index  to
{       the  unused  entry.   IF unused_entry_found = FALSE then this value is
{       undefined.
{
{ UNUSED_ENTRY_FOUND: (output) This parameter returns whether an unused  entry
{       was found in the member vsn list of the master volume set table.
{       NOTE: This routine makes NO attempt to create an unused entry  if  one
{       does not exist at the time of this call.
{
