*-- Author : S.Burke
      SUBROUTINE FFTRUE(JTRUE)
**********************************************************************                                        
*                                                                    *                                        
* Fill the TRUE array from the track JTRUE                           *                                        
*                                                                    *                                        
**********************************************************************                                        
      INTEGER FFCHG
*KEEP,FKNPL.                                                                                                  
*                                                                                                             
* Per-track values can go in H1WORK; note that LTRUE and LFIRST must                                          
* be set at least per event.                                                                                  
*                                                                                                             
* This is about 36k words long; the remaining common blocks are                                               
* about 3.6k in total. Some of this could be in /H1WORK/, but the                                             
* blocks would have to be reorganised.                                                                        
*                                                                                                             
* /FKPROJ/                                                                                                    
* /FKFILT/                                                                                                    
* /FKSMTH/                                                                                                    
* /FKINT/                                                                                                     
* /FKRSID/                                                                                                    
* /FKTRUE/                                                                                                    
* /FKDBG/                                                                                                     
*KEEP,FFSTEE.                                                                                                 
*KEEP,FKCONS.                                                                                                 
*KEEP,FKTRUE.                                                                                                 
*KEEP,BCS.                                                                                                    
*KEEP,STFUNCT.                                                                                                
*     index of element before row number IROW                                                                 
*     index of L'th element  of row number IROW                                                               
*     L'th integer element of the IROW'th row of bank with index IND                                          
*     L'th real element of the IROW'th row of bank with index IND                                             
*KEND.                                                                                                        
**********************************************************************                                        
* Find the starting track bank (if it exists)                                                                 
      INDFS = NLINK('FS  ',0)
* Find the track with the right STR number                                                                    
* This should be impossible, but ...                                                                          
* Find the simulated track and vertex banks                                                                   
* Get the track parameters at the vertex                                                                      
      ICHG = FFCHG(IPDG)
* Can be a gamma (if secondaries are stacked), which screws up FKTRAN                                         
* Assemble a KF-type state vector                                                                             
      CALL FKNORM(S,IFAIL)
* Translate to each plane in succession                                                                       
         CALL FKTRAN(DZ,Z,S,TRUE(1,JPL),DTRAN)
* Use FRPF/FRRF banks if available                                                                            
      CALL FFXTRP(JTRUE,S)
*