MAPLUN(3F)							    MAPLUN(3F)

NAME    [Toc]    [Back]

     maplun - returns the integer file descriptor for a	Fortran	logical	unit
     number

SYNOPSIS    [Toc]    [Back]

     maplun (lun)
     integer*4 lun

DESCRIPTION    [Toc]    [Back]

     This function returns the file descriptor given a Fortran logical unit
     number.

DIAGNOSTICS    [Toc]    [Back]

     Success is	indicated by a non-negative return value.  A negative return
     value indicates an	error.	The value of errno can be examined to
     determine the cause of the	error.

NOTES    [Toc]    [Back]

     This function cannot be used on indexed files since each Fortran indexed
     file is represented by two	physical files and this	function cannot	map a
     single Fortran logical unit to two	file descriptors. Also,	the indexed
     file internal format is proprietary and cannot be modified	by the user
     directly so this function,	or a similar function, will not	help in	that
     respect.


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