!=====================================================================
! NGVV: Vectors, A Vector Field Plotting Utility
!=====================================================================
!
! VECTORS allows user to plot vector fields given two arrays
! containing the components of the vectors on a uniform grid in a
! user-defined coordinate system. In addition, the user may pass in
! another array of scalar data defined over the same grid space
! independent of but presumably related in some fashion to the vector
! data. The utility will then color each vector based on the scalar
! value at the same grid point. Alternatively, the user can choose
! to color the vectors based on the vector magnitude at the grid point.
!
! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
! set/Get internal parameters
! ~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
! NG_VVRSET to reset all parameters to their default values.
!
! NG_VVSETC to give a value of type CHARACTER to a parameter.
! NG_VVSETI to give a value of type INTEGER to a parameter.
! NG_VVSETR to give a value of type REAL to a parameter.
!
! NG_VVGETC to get a value of type CHARACTER.
! NG_VVGETI to get a value of type INTEGER.
! NG_VVGETR to get a value of type REAL.
!
! NG_VVGETMAPINFO to get information from the mapping common data
!                 available to the user subroutine VVUMXY
!
! ~~~~~~~~~~~~~~~~
! Working Routines
! ~~~~~~~~~~~~~~~~
!
! NG_VVINIT to initialize the vector field plot.
!
! NG_VVECTR to draw the vectors.
!
! NG_VVUDMV, Example version of user masked drawing program
!
! ~~~~~~~~~~~~~~~~
! Obsolete Entries
! ~~~~~~~~~~~~~~~~
!
! NG_EZVEC  to plot a vector field in a single call.
!
! NG_VELVCT to plot a vector field in a single call.
!
!---------------------------------------
!
! Note: CNCARG adding a "optional dummy subprogram arguments", VVUMXY,
!       to the VECTOR routine
!
!       NG_VVECTR( U, V, P, IAM, VVUDMV, WRK, VVUMXY )
!
!---------------------------------------------------------------------
! Parameter  Brief description                           Fortran type
!---------------------------------------------------------------------
! AMN        Arrow head MiNimum size                     Real
! AMX        Arrow head MaXimum size                     Real
! CLR        Array of GKS CoLoR indices                  Integer array
! CPM        ComPatibility Mode                          Integer
! CTV        Color Threshold Value control               Integer
! DMN        NDC MiNimum vector size                     Real, read-only
! DMX        NDC MaXimum vector size                     Real, read-only
! DPF        Vector label Decimal Point control Flag     Integer
! LBC        Vector LaBel Color                          Integer
! LBL        Vector LaBeL flag                           Integer
! LBS        Vector LaBel character Size                 Real
! LWD        Vector Line WiDth                           Real
! MAP        MAP transformation code                     Integer
! MNC        MiNimum vector text block Color             Integer
! MNP        MiNimum vector text block Positioning mode  Integer
! MNS        MiNimum vector text block character Size    Real
! MNT        MiNimum vector Text string                  Character*36
! MNX        MiNimum vector text block X coordinate      Real
! MNY        MiNimum vector text block Y coordinate      Real
! MSK        MaSK to area map flag                       Integer
! MXC        MaXimum vector text block Color             Integer
! MXP        MaXimum vector text block Positioning mode  Integer
! MXS        MaXimum vector text block character Size    Real
! MXT        MaXimum vector Text string                  Character*36
! MXX        MaXimum vector text block X coordinate      Real
! MXY        MaXimum vector text block Y coordinate      Real
! NLV        Number of colors LeVels                     Integer
! PAI        Parameter Array Index                       Integer
! PLR        PoLaR input mode                            Integer
! PMN        MiNimum scalar array value                  Real, read-only
! PMX        MaXimum scalar array value                  Real
! PSV        P array Special Value                       Real
! SET        SET call flag                               Integer
! SPC        SPecial Color                               Integer
! SVF        Special Value Flag                          Integer
! TRT        TRansformation Type                         Integer
! TVL        Array of Threshold VaLues                   Real array
! USV        U array Special Value                       Real
! VFR        Minimum Vector FRactional length            Real
! VHC        Vector High Cutoff value                    Real
! VLC        Vector Low Cutoff value                     Real
! VRL        Maximum Vector Realized Length              Real
! VMN        MiNimum Vector magnitude                    Real, read-only
! VMX        MaXimum Vector magnitude                    Real, read-only
! VPB        ViewPort Bottom                             Real
! VPL        ViewPort Left                               Real
! VPO        Vector POsitioning mode                     Integer
! VPR        ViewPort Right                              Real
! VPS        ViewPort Shape                              Real
! VPT        ViewPort Top                                Real
! VST        Vector STatistics output flag               Integer
! VSV        V array Special Value                       Real
! WDB        WinDow Bottom                               Real
! WDL        WinDow Left                                 Real
! WDR        WinDow Right                                Real
! WDT        WinDow Top                                  Real
! XC1        X Coordinate at index 1                     Real
! XCM        X Coordinate at index M                     Real
! XIN        X-axis array INcrement (grid)               Integer
! YC1        Y Coordinate at index 1                     Real
! YCN        Y Coordinate at index N                     Real
! YIN        Y-axis array INcrement (grid)               Integer
! ZFC        Zero Field text block Color                 Integer
! ZFP        Zero Field text block Positioning mode      Integer
! ZFS        Zero Field text block character Size        Real
! ZFT        Zero Field Text string                      Character*36
! ZFX        Zero Field text block X coordinate          Real
! ZFY        Zero Field text block Y coordinate          Real
!=====================================================================
! Refer "NCAR menu" for interfacing VECTORS in detail
!=====================================================================