General information about SPICE SCL-kernels                                   
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   In the SPICE system, the Spacecraft Clock (or SCL) -kernel contains        
   information required to perform a mapping between Ephemeris time           
   (ET) and spacecraft on-board time (SCLK).                                  
                                                                              
   The spacecraft clock coefficient information contained in an SCLK          
   file can be manipulated by a collection of subroutines to provide a        
   transformation between Ephemeris and spacecraft on-board times.            
   These subroutines are part of the SPICE library, the major                 
   component of the SPICE Toolkit. The routines needed are integrated         
   into a user's application programs. For information on the SPICE toolkit   
   and/or how to obtain it, please consult SPICE_INST.CAT and                 
   SOFT.CAT.                                                                  
                                                                              
   Refer to the SCLK.REQ document provided with the Toolkit to get more       
   information about conversion between ET and spacecraft clock times.        
                                                                              
Mars Express SCLK Files                                                       
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   This file describes the contents of the DATA/SCLK directory of the         
   Mars Express SPICE dataset.                                                
                                                                              
   SCLK files are created from the information contained in the ESOC's        
   DDID Time Correlation Packets.                                             
                                                                              
   All SCLK files (*.TSC) contained in this directory are unix text           
   files. In order to be used in a non-UNIX environment, they have to         
   be converted to the appropiate end-line convention. For example, the       
   lines have to be terminated by a <CR><LF> combination for Windows          
   platforms.                                                                 
                                                                              
                                                                              
Mars Express SCL-Kernels Contained in this Data Set                           
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   The following MARS EXPRESS SCL-kernels are provided in this data set:      
                                                                              
       MEX_yymmdd_STEP.TSC  This file is a SPICE spacecraft clock (SCLK)      
                            kernel containing information required for        
                            the Mars Express spacecraft on-board clock to UTC 
                            conversion. This file provides the same time      
                            information that the Time Correlation packets     
                            released via DDS, with the exception of 60        
                            seconds before the starting time of each          
                            packet,during which the clock rate was sightly    
                            adjusted to make the correlation function         
                            continuous. This file was released                
                            on yy-mm-dd.                                      
                                                                              
   Note that when several SCLK kernels are provided in the dataset, the       
   most recent one supersedes all the others.                                 
                                                                              
Kernel File Details                                                           
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   The most detailed description of the data in an SCLK file is               
   provided in metadata included inside the description area of the           
   file. This information can be viewed using any text editor program.        
                                                                              
   At least a basic knowledge of the SPICE system is needed in                
   order to use this kernels. The SPICE toolkit provides versions             
   in Fortran (SPICELIB), C (CSPICE) and IDL (icy), and the user              
   can choose any one that suits him/her.                                     
                                                                              
   The SPICELIB routine FURNSH, CSPICE function furnsh_c, and icy             
   routine cspice_furnsh load a kernel file into the kernel pool              
   as shown below.                                                            
                                                                              
      CALL FURNSH ( 'kernel_name' )                                           
      furnsh_c    ( ''kernel_name'' );                                        
      cspice_furnsh, 'kernel_name'                                            
                                                                              
   In the case when two or more files contain data overlapping in             
   time for a given object, for binary kernels, the file loaded               
   last takes precedence.                                                     
                                                                              
   If two (or more) text kernels assign value(s) using the '='                
   operator to identical keywords, the data value(s) associated               
   with the last loaded occurrence of the keyword are used -all               
   earlier values have been replaced with the last loaded                     
   value(s).