	SUBROUTINE MR_AVAILABLE ( mr )

*
*
*  This software was developed by the Thermal Modeling and Analysis
*  Project(TMAP) of the National Oceanographic and Atmospheric
*  Administration''s (NOAA) Pacific Marine Environmental Lab(PMEL),
*  hereafter referred to as NOAA/PMEL/TMAP.
*
*  Access and use of this software shall impose the following
*  obligations and understandings on the user. The user is granted the
*  right, without any fee or cost, to use, copy, modify, alter, enhance
*  and distribute this software, and any derivative works thereof, and
*  its supporting documentation for any purpose whatsoever, provided
*  that this entire notice appears in all copies of the software,
*  derivative works and supporting documentation.  Further, the user
*  agrees to credit NOAA/PMEL/TMAP in any publications that result from
*  the use of this software or in any product that includes this
*  software. The names TMAP, NOAA and/or PMEL, however, may not be used
*  in any advertising or publicity to endorse or promote any products
*  or commercial entity unless specific written permission is obtained
*  from NOAA/PMEL/TMAP. The user also understands that NOAA/PMEL/TMAP
*  is not obligated to provide the user with any support, consulting,
*  training or assistance of any kind with regard to the use, operation
*  and performance of this software nor to provide the user with any
*  updates, revisions, new versions or "bug fixes".
*
*  THIS SOFTWARE IS PROVIDED BY NOAA/PMEL/TMAP "AS IS" AND ANY EXPRESS
*  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*  ARE DISCLAIMED. IN NO EVENT SHALL NOAA/PMEL/TMAP BE LIABLE FOR ANY SPECIAL,
*  INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
*  RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
*  CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION, ARISING OUT OF OR IN
*  CONNECTION WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE. 
*
*
* flag that the specified variable is available to be used as a component and
* to be deleted should memory space be tight

* programmer - steve hankin
* NOAA/PMEL, Seattle, WA - Tropical Modeling and Analysis Program
* written for VAX computer under VMS operating system
*
* V200:  6/12/89
*        2/12 *kms* Add E and F dimensions (use nferdims in tmap_dims.parm)

        IMPLICIT NONE
        include 'tmap_dims.parm'
	include 'ferret.parm'
	include 'xvariables.cmn'

* calling argument declarations:
	INTEGER mr

* internal variable declarations:
	INTEGER last_head

* if this variable held "essential" data, flag that it no longer is essential
	   IF ( mr_protected( mr ) .EQ. mr_temporary	
     .	  .OR.  mr_protected( mr ) .EQ. mr_in_progress
     .	  .OR.  mr_protected( mr ) .GT. mr_not_protected    ) THEN
	      essential_mem = essential_mem - mr_size(mr)
	   ENDIF

* set flag that it is available for use and for deletion
	mr_protected( mr ) = mr_not_protected

! temp diag
	IF (mr_del_flink(mr) .NE. unspecified_int4) 
     .		WRITE (6,*)' crptn: mr_available'

* insert the variable at the head of the deletion priority chain
	last_head = mr_del_flink(0)
	mr_del_blink(mr) = 0
	mr_del_flink(mr) = last_head
	mr_del_flink(0)  = mr
	mr_del_blink(last_head) = mr

	RETURN
	END

