Update a character column entry in a specified EK record. 

   EK 

   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   handle     I   EK file handle. 
   segno      I   Index of segment containing record. 
   recno      I   Record to which data is to be updated. 
   column     I   Column name. 
   nvals      I   Number of values in new column entry. 
   vallen     I   Declared length of character values.
   cvals      I   Character values comprising new column entry. 
   isnull     I   Flag indicating whether column entry is null. 

   handle         is the handle of an EK file open for write access. 

   segno          is the index of the segment containing the column entry 
                  to be updated.  EK segment numbers range from
                  0 to N-1, where N is the number of segments
                  in the kernel.

   recno          is the index of the record containing the column entry
                  to be updated.  This record number is relative to the start 
                  of the segment indicated by segno; the first 
                  record in the segment has index 0. 

   column         is the name of the column containing the entry to 
                  be updated. 

   nvals          is the number of elements in the new value to be inserted
                  into the specified column.

   vallen         is the length of the strings in the cvals array, where
                  the length includes space for null terminators.  

                  If the  column has fixed-size entries, then nvals 
                  must equal the entry size for the specified column. 


   cvals          is the set of replacement values themselves.  The values are 
                  written into the specified column and record. 

                  The array cvals should be declared with dimensions

                     [nelts][vallen]

                  where nelts is greater than or equal to nvals.

   isnull         is a logical flag indicating whether the entry is 
                  null.  If isnull is SPICEFALSE, the column entry 
                  defined by nvals and cvals is added to the 
                  specified kernel file. 

                  If isnull is SPICETRUE, nvals and cvals are ignored:
                  no data are written into the specified column entry. 
                  The column entry is marked as a null value.

                  If the column has fixed-length, variable-size 
                  entries, the number of entries is considered to 
                  be 1. 

   None.  See $Particulars for a description of the effect of this 
   routine. 

   None. 

   This routine operates by side effects:  it modifies the named 
   EK file by replacing a specified character column entry. 

   1)  Replace the value in the third record of the column CCOL in 
       the fifth segment of an EK file designated by handle.  Set 
       the new value to "999". 

          #include "SpiceUsr.h"
             .
             .
             .
          ekucec_c ( handle, 4, 2, "CCOL", 1, 4, "999", SPICEFALSE );


    2)  Same as (1), but this time insert a null value.  The argument 
       "999" is ignored because the null flag is set to SPICETRUE 

          #include "SpiceUsr.h"
             .
             .
             .
          ekucec_c ( handle, 4, 2, "CCOL", 1, 4, "999", SPICETRUE );


   3)  Replace the entry in the third record of the column CARRAY in 
       the fifth segment of an EK file designated by handle.  Set 
       the new value using an array cbuff of 10 string values. 
       We assume cbuff was declared as shown:

          SpiceChar cbuff[10][CBLEN];



          #include "SpiceUsr.h"
             .
             .
             .
          ekucec_c ( handle,  4,      2,      "CARRAY", 
                     10,      CBLEN,  cbuff,  SPICEFALSE );

   None. 

   1)  If handle is invalid, the error will be diagnosed by routines 
       called by this routine. 

   2)  If segno is out of range, the error will be diagnosed by 
       routines called by this routine. 

   3)  If column is not the name of a declared column, the error 
       will be diagnosed by routines called by this routine. 

   4)  If column specifies a column of whose data type is not 
       character, the error SPICE(WRONGDATATYPE) will be 
       signaled. 

   5)  If recno is out of range, the error will be diagnosed by 
       routines called by this routine. 

   6)  If the specified column has fixed-size entries and nvals 
       does not match this size, the error will be diagnosed by 
       routines called by this routine. 

   7)  If the specified column has variable-size entries and nvals 
       is non-positive, the error will be diagnosed by routines 
       called by this routine. 

   8)  If an attempt is made to add a null value to a column that 
       doesn't take null values, the error will be diagnosed by 
       routines called by this routine. 

   9)  If column specifies a column of whose class is not 
       a character class known to this routine, the error 
       SPICE(NOCLASS) will be signaled. 

   10) If an I/O error occurs while reading or writing the indicated 
       file, the error will be diagnosed by routines called by this 
       routine. 

   11) If the input string pointer for the column name is null, the error 
        SPICE(NULLPOINTER) will be signaled.

   12) If the input string column name has length zero, the error 
       SPICE(EMPTYSTRING) will be signaled.

   13) If the string pointer for cvals is null, the error
       SPICE(NULLPOINTER) will be signaled.

   14) If the string length vallen is less than 2, the error 
       SPICE(STRINGTOOSHORT) will be signaled.

   See the EK Required Reading for a discussion of the EK file 
   format. 

   N.J. Bachman   (JPL) 

   None. 

   -CSPICE Version 1.0.0, 28-AUG-2001 (NJB)

   replace character entry in an EK column