SUBROUTINE GCB_GETR( NAME, OK, RVAL, STATUS )
*+
*  Name:
*     GCB_GETR

*  Purpose:
*     Get scalar REAL graphics attribute value

*  Language:
*     Starlink Fortran

*  Invocation:
*     CALL GCB_GETR( NAME, OK, RVAL, STATUS )

*  Description:
*     Gets scalar REAL graphics attribute value from the current GCB.
*     An attribute may or may not have a current value - OK is set 
*     accordingly. If the attribute has no value then RVAL is not 
*     altered.

*  Arguments:
*     NAME = CHARACTER*(*) (given)
*        Name of attribute to be read
*     OK = LOGICAL (returned)
*        Attribute value is set?
*     RVAL = REAL (returned)
*        The value of the attribute
*     STATUS = INTEGER (given and returned)
*        The global status.

*  Examples:
*     {routine_example_text}
*        {routine_example_description}

*  Pitfalls:
*     {pitfall_description}...

*  Notes:
*     {routine_notes}...

*  Prior Requirements:
*     {routine_prior_requirements}...

*  Side Effects:
*     {routine_side_effects}...

*  Algorithm:
*     {algorithm_description}...

*  Accuracy:
*     {routine_accuracy}

*  Timing:
*     {routine_timing}

*  External Routines Used:
*     {name_of_facility_or_package}:
*        {routine_used}...

*  Implementation Deficiencies:
*     {routine_deficiencies}...

*  References:
*     GCB Subroutine Guide : http://www.sr.bham.ac.uk/asterix-docs/Programmer/Guides/gcb.html

*  Keywords:
*     package:gcb, usage:public

*  Copyright:
*     Copyright (C) University of Birmingham, 1995

*  Authors:
*     DJA: David J. Allan (Jet-X, University of Birmingham)
*     {enter_new_authors_here}

*  History:
*      4 Mar 1996 (DJA):
*        Generic version.
*     {enter_changes_here}

*  Bugs:
*     {note_any_bugs_here}

*-
      
*  Type Definitions:
      IMPLICIT NONE              ! No implicit typing

*  Global Constants:
      INCLUDE 'SAE_PAR'          ! Standard SAE constants
      INCLUDE 'GCB_PAR'

*  Global variables :
      INCLUDE 'GCB_CMN'

*  Arguments Given:
      CHARACTER*(*)		NAME

*  Arguments Returned:
      LOGICAL			OK
      REAL			RVAL

*  Status:
      INTEGER 			STATUS             	! Global status

*  External References:
      LOGICAL			GCB_NULL
        EXTERNAL		GCB_NULL

*  Local Variables:
      CHARACTER*16 		FMT,TYPE

      INTEGER 			DISP,SIZ
*.

*  Check inherited global status.
      IF ( STATUS .NE. SAI__OK ) RETURN

*  Locate named attribute
      CALL GCB_LOCSCAL( NAME, DISP, SIZ, FMT, TYPE, STATUS )

*  Value is defined?
      OK = .NOT. GCB_NULL( %VAL(G_MEMPTR), DISP, SIZ, STATUS )

*  Extract value if ok
      IF ( OK ) THEN
        CALL GCB_GETR_SUB( %VAL(G_MEMPTR), DISP, SIZ, FMT, RVAL,
     :                       STATUS )
      END IF

*  Report any errors
      IF ( STATUS .NE. SAI__OK ) CALL AST_REXIT( 'GCB_GETR', STATUS )

      END