S. Hagopian
                                                            May, 14 ,1989
                                                            Rev. June 15, 1989
                      USER_LEGO.DOC

     A. INTRODUCTION

        Users can book and fill stand-alone LEGO banks, which can be plotted
     using the D0 display package PIXIE. Utilities exist for booking a LEGO
     bank, finding the pointer to the bank, giving the title of a bank, giving
     the total number of LEGO banks, and printing the contents of a bank.
     The PIXIE command execution routine, PLZEXE, allow the user to plot
     a LEGO bank by entering the bank number. The sum of 2 LEGO banks can
     also be plotted.  Parameters can be changed interactively to set the
     number of X and Y bins, the X and Y limits of the plot, the cut value
     of Z, and the labels of the axes.

     B. UTILITY ROUTINES

        These routines are a part of ZEBRA_UTIL in GENERAL.OLB.

        1. SUBROUTINE BKLEGO(TITLE,NTRIPL,LLEGO)- books 1 stand-alone LEGO bank

           Input:
                 TITLE [C*32] - Character string for title 
                 NTRIPL [I] - number of triplet data points (X,Y,Z,)
           Output:
                 LLEGO = Pointer to newly created bank


           ENTRY GZLEGO(NUMB)- INTEGER FUNCTION, returns the ZEBRA 

                                  pointer to the LEGO bank number NUMB

        2. FUNCTION NLEGOS()- Returns the total number of  LEGO banks.(INTEGER)


        3. SUBROUTINE LEGOTT(LEGO,TITLE) -returns the title of the bank

           Input:
                 LEGO [I] - pointer to the bank
           Output:  
                 TITLE [C*32]- Title of the bank 
       
        4. SUBROUTINE PRLEGO(PRUINT,LLEGO,NLEGO,CFL,IFL)-prints contents of bank

           Input:

                PRUNIT [I] - Unit number for printout

                LLEGO [I] - Pointer to the one bank (CFL = 'ONE') or to the
                            first of a linear structur (CRL='LINEAR').

                NLEGO [I] -Bank number, used only if CFL='ONE' and LLEGO=0.

                CFL [C*] - Character flag, other input depends on it's value:
                         'ONE' : LLEGO points to a bank; if LLEGO =0, NLEGO 
                                 is the bank number.
                         'LINEAR' : LLEGO points to the first bank of the
                                    linear structur
                         'ALL' : Prints all banks with name 'LEGO'

                IFL [I] - Defines the amount of printing: 0 means full
                          printout, .NE.0 print only title



     C. STRUCTURE OF LEGO BANK

        (This can be found in  D0$ROOT:[ZEB.STAND_ALONE]LEGO.ZEB)

C=======================================================================
C
C  Bank Name : LEGO
C  Author    : Serban D. Protopopescu
C  Date      : 15-FEB-1989
C  Tree description : none
C
C  Bank description : stand alone banks for lego plots
C
C     LQ     Q/IQ
C-----------------------------------------------------------------------
C      0          Next   link to LEGO
C     +1          Up     link to none
C     +2          Origin link to none or previous LEGO
C.......................................................................
C             -5         Bank number
C             -4         Bank name, 'LEGO'
C             -3         NL = 0
C             -2         NS = 0
C             -1         ND = 3*(number of triplets)+10
C              0         Status
C             +1         vrsn (=1)
C             +2         number of triplets
C             +3         title 1
C             +4         title 2
C             +5         title 3
C             +6         title 4
C             +7         title 5
C             +8         title 6
C             +9         title 7
C             +10        title 8
C             +11        x
C             +12        y
C             +13        z
C             +14        x
C              .         .
C              .         .
C=======================================================================














     D. INTERFACE TO PIXIE

        The program D0USER already has an interface to PIXIE with a call to
        PXMAIN(NOMORE). In order to get the USER LEGO display, the user must
        LINK in LOGICAL FUNCTION PXEXEC(), which can either have a call to
        LOGICAL FUNCTION PLZEXE() or can test the command PLEGOZ directly. 


      LOGICAL FUNCTION PXEXEC
C----------------------------------------------------------------------
C-
C-   Purpose and Methods : Call subroutine PLZEXE - dispatching routine
C-                         for USER LEGO plot
C-
C-   Created  30-NOV-1988 S. Hagopian
C----------------------------------------------------------------------
      IMPLICIT NONE
      LOGICAL PLZEXE
C----------------------------------------------------------------------
      IF(PLZEXE())THEN
        PXEXEC = .TRUE.
      ELSE
        PXEXEC = .FALSE.
      ENDIF
  999 RETURN
      END

        (See D0$PIXIE:SOURCE:PLZEXE.FOR)        
 
    E. SCREEN and PARAMETER FILES

       The user may either use the standard screen and parameter files directly:
       
       DEFINE PXPARAMS D0$PIXIE$DATA:USER_LEGO.PXPARA (in PIXIE VER 1.44)
       DEFINE PXSCREEN D0$PIXIE$DATA:USER_LEGO.PXSCREEN (in PIXIE VER 1.44)

       or merge these files with other PIXIE screen and parameter files

       Note: The .PXPARA files are an ASCII file and can be merged with EVE,
             the .SCREEN files are binary files and can be merged using the
             EDIT SCREEN menu in PIXIE.
       
       1. USER_LEGO.PXPARA

PARAMETER        TYPE      DEFAULT          USE
----------       ----      --------  ---------------------------
LEGO NX           [I]          64    Number of X bins
LEGO XMIN         [F]      0.0000    minimum value of X
LEGO XMAX         [F]         64.    maximum value of X
LEGO NY           [I]          74    Number of Y bins
LEGO YMIN         [F]     -3.7000    minimum value of Y
LEGO YMAX         [F]      3.7000    maximum value of Y
LEGO ZCUT         [F]      0.0000    data with Z<ZCUT will not be plotted
LEGO ZMAX         [F]     -1.0000    maximum value of Z plotted;
                                     ZMAX<0 to have ZMAX determined from data
LEGO ALLGRID      [L]           F    F for every Nth grid line to be plotted
                                     T for every grid line to be plotted
LEGO XTITL        [A]         PHI    title for X axis
LEGO YTITL        [A]         ETA    title for Y axis
LEGO ZTITL        [A]          ET    title for Z axis
X CHAR SIZE       [F]      0.0221    Menu X character size
Y CHAR SIZE       [F]      0.0442    Menu Y character size
STRING QUALITY    [I]           1    1 for hardware char, 4 for software char
WAIT FOR MENU     [L]           F    F - menu appears immediately,
                                     T menu does not appear until hit keyboard 
RETAINED MENU     [L]           F    F - menu does not appear on hardcopy
                                     T - menu appears on hardcopy
PRINT HARDCOPY    [L]           F    F - harcopy written to file
                                     T - hardcopy printed immediately on
                                         queue SYS$PRINT
SCREEN FRACTION   [F]      1.0000    Fraction of screen to use
KEYBOARD INPUT    [L]           F    F - mouse input only for GPV driver
                                     T - keyboard input only for GPV driver
                                     (VT240,T10,T14 and S04 allow intermixed 
                                      cursor and keyboard input)

     2. USER_LEGO.SCREEN 

   The action (command execution) routine for  USER_LEGO screen is PLEGOZ.
   The viewing window limits of the plot have the values in USER_LEGO.SCREEN of:
     XMIN=-1000.
     XMAX=1000.
     YMIN=-1000.
     YMAX=1000.

    With these default values, the program tries to automatically adjust the
    viewing window for any NX by NY size plot. It is not always successful.
    If the USER_LEGO plot is cut off or does not appear as you wish, the window
    values can be changed interactively by choosing the menu item EDIT SCREEN
    in the MAIN MENU or the item MODIFY SCREEN in the USER LEGO sub-menu.
    Choose the item "SET JWINDOW". The program will print the current value
    it has calculated. Change these values as necessary to get the desired
    view. Remember to save these values by choosing the menu item "WRITE
    SCREEN FILE" in the menu EDIT SCREENS, if you want to use the new values
    when running your job again.

F. RUNNING D0USER with USER_LEGO

          The item 'DISPLAY EVENT" can be chosen in the main D0MENU menu, 
          and the user giving a list of events to be displayed,
          or -1 to display the next N events, or by choosing the item
          "SET INTERRUPT MENU" in the main D0USER
          menu and choosing EVENT DISPLAY in the INTERRUPT menu.

          The USER_LEGO screen menu has 2 items:
           "USER LEGO" 
           "USER LEGO SUM"
          If "USER LEGO" is chosen, the total number of booked LEGO 
          banks is printed on the screen and the user must enter the
          bank number to be displayed. If "USER LEGO SUM" is chosen the user
          must enter the 2 bank numbers whose data is to be added.
          The 2 parts are show in different colors.
               



     F. SUMMARY

        The following is a summary of the user action necessary to get a 
         USER LEGO plot:

       1. LINK a version of SUBROUTINE PXEXEC with D0USER which calls 
          LOGICAL FUNCTION PLZEXE.

       2. Define the screen and parameter files using USER_LEGO.PXPARA
          and USER_LEGO.SCREEN as examples.

       3. Add user routine  to book and fill LEGO banks, starting with 
          location Q(LLEGO+11) (See LEGO.ZEB Section C)

       4. Run D0USER and choose the following menu items:
          "EVENT DISPLAY"
             then choose
            "USER LEGO"
                 or
            "USER LEGO SUM"
                Enter the bank number(s) to be plotted.

       5. Modify the parameter and screen files as necessary to get
          desired plot.

     NOTE: This facility assumes a small number of LEGO  banks. The binning
          can be changed by choosing the menu item "MODIFY PARAMETERS"
          and varying NX and NY. If banks with various types of data are
          being filled, the user may want to write a new interface routine
          using PLEGOZ as an example. 

          For further information about the utilities to make general LEGO
          plots see D0$ROOT:[PIXIE]LEGO_REF.DOC.