%N grglun %F $MIR/opt/local/var/macports/build/_opt_PPCSnowLeopardPorts_science_miriad/miriad/work/miriad-4.3.8/borrow/pgplot/sys/grglun.f
%D Get a Fortran logical unit number (Sun/Convex-UNIX)
%B
      SUBROUTINE GRGLUN(LUN)
      INTEGER LUN

 Get an unused Fortran logical unit number. 
 Returns a Logical Unit Number that is not currently opened.
 After GRGLUN is called, the unit should be opened to reserve
 the unit number for future calls.  Once a unit is closed, it
 becomes free and another call to GRGLUN could return the same
 number.  Also, GRGLUN will not return a number in the range 1-9
 as older software will often use these units without warning.

 Arguments:
  LUN    : receives the logical unit number, or -1 on error.
