Insert an item into a character set. 

   SETS 

   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   item       I   Item to be inserted. 
   set       I/O  Insertion set. 

   item        is an item which is to be inserted into the specified
               set. item may or may not already be an element of the
               set.  Trailing blanks in item are not significant.


   set         is a CSPICE set.  set must be declared as a character
               SpiceCell. 

               On input, set  may or may not contain the input item 
               as an element. 

   set         on output contains the union of the input set and 
               the singleton set containing the input item.

   None. 

   None. 

   1) In the following example, the element "PLUTO" is removed from 
      the character set planets and inserted into the character set 
      asteroids. 

         #include "SpiceUsr.h"
                .
                .
                .
         /.
         Declare the sets with string length NAMLEN and with maximum
         number of elements MAXSIZ.
         ./
         SPICECHAR_CELL ( planets,   MAXSIZ, NAMLEN );
         SPICECHAR_CELL ( asteroids, MAXSIZ, NAMLEN );
                .
                .
                .
         removc_c ( "PLUTO", &planets   );
         insrtc_c ( "PLUTO", &asteroids ); 


      If "PLUTO" is not an element of planets, then the contents of 
      planets are not changed. Similarly, if "PLUTO" is already an 
      element of asteroids, the contents of asteroids remain unchanged. 

      Because inserting an element into a set can increase the 
      cardinality of the set, an error may occur in the insertion 
      routines. 

   1)  String comparisons performed by this routine are Fortran-style:
       trailing blanks in the input set or key value are ignored.
       This gives consistent behavior with CSPICE code generated by
       the f2c translator, as well as with the Fortran SPICE Toolkit.

       Note that this behavior is not identical to that of the ANSI
       C library functions strcmp and strncmp.

   1) If the input set argument is a SpiceCell of type other than
      character, the error SPICE(TYPEMISMATCH) is signaled.

   2) If the insertion of the element into the set causes an excess 
      of elements, the error SPICE(SETEXCESS) is signaled. 

   3) If the input set argument does not qualify as a CSPICE set, 
      the error SPICE(NOTASET) will be signaled.  CSPICE sets have
      their data elements sorted in increasing order and contain
      no duplicate data elements.

   4) If the input string pointer is null, the error SPICE(NULLPOINTER)
      is signaled.

   None. 

   N.J. Bachman    (JPL) 
   C.A. Curzon     (JPL) 
   W.L. Taber      (JPL) 
   I.M. Underwood  (JPL) 

   None. 

   -CSPICE Version 2.0.0, 01-NOV-2005 (NJB)

       Bug fix:  when the item to be inserted would, after
       truncation to the set's string length, match an item
       already in the set, no insertion is performed.  Previously
       the truncated string was inserted, corrupting the set.

       Long error message was updated to include size of
       set into which insertion was attempted.

   -CSPICE Version 1.0.0, 21-AUG-2002 (NJB) (CAC) (WLT) (IMU)

   insert an item into a character set