*****  File INDXERRS.TXT                                                      
                                                                              
     This file contains information about errors in index files (*.IDX) and   
associated headers (*.HDR) and labels (*.LBL) that have been detected in      
CD-ROM Volumes 19-22 (HAL_0019--HAL_0022).  The specific indices are          
QUIK_0nn.* (the so-called "Quick Look indices", where nn=19-22), and          
CDSTRUCT.*.  The errors in the QUIK_0nn indices have been corrected in the    
/SUMMARY/INDEX subdirectory of this CD-ROM.                                   
                                                                              
     There are several kinds of errors:                                       
                                                                              
1.)  The number of table rows listed in the FITS header and PDS label files   
were not always correct; the relevant parameters were NAXIS2 (header) and     
RECORDS_FILE and ROWS (label). There were 4 such errors as shown below.       
                                                                              
     file          correct          FITS           PDS                        
     name           value          header         label                       
________________________________________________________                      
   quik_019        10932           10932         10902                        
   quik_020         8885            8885         25313                        
                                                                              
   CDSTRUCT (19)   32001           32001         31523                        
   CDSTRUCT (20)   25718           25716         25718                        
________________________________________________________                      
                                                                              
                                                                              
2.)  The second kind of error pertains to the CDSTRUCT.IDX files.  Several of 
the files have the wrong subdirectories listed for the file CDSTRUCT.IDX.  The
correct value for the subdirectory of CDSTRUCT.IDX is INDEX.                  
                                                                              
3.)  On HAL_0020 through HAL_0022, the value of NAXIS3 in QUIK_0nn.IDX is     
incorrectly given as the value of NAXIS2 (for the same file) whenever NAXIS=2;
NAXIS3 should, of course, be zero in these instances.  Moreover, for FITS     
tables (extension =.TAB) the values of NAXIS1 and NAXIS2 are frequently zero, 
or else they are non-zero and the value of NAXIS2 is repeated in the NAXIS3   
column.                                                                       
                                                                              
4.)  On HAL_0019 the QUIK_019.IDX file has NAXIS=2 for FITS tables, all other 
problems mentioned in 3.) above being absent.  The "policy" we have adopted   
for FITS tables in the corrected versions of QUIK_0nn.IDX on this final mixed 
disc (in the /SUMMARY/INDEX directory) is as follows:                         
                                                                              
       NAXIS = 0 (keyword value in primary header)                            
       NAXIS1 = value in secondary header                                     
       NAXIS2 = value in secondary header                                     
                                                                              
We have adopted this "hybrid" approach in order to differentiate the FITS     
tables from, say, 2-dimensional images (NAXIS=2), while at the same time      
giving some indicator, via NAXIS1 and NAXIS2, of how much information is      
contained in the table.  Additional indication that a file is a FITS table is 
provided in QUIK_0nn.IDX via the filename extension; for a table it is .TAB.