Synopsis:
   $setitem(<array> <item#> <data>)

Technical:
   This function creates a new cell in the specified array.  If the array
   does not exist, the client will try to create it.

Practical:
   This function is the single doorway into EPIC's arrays.  It must be used
   to create or add to an array.  The array name may be anything,
   consisting of any characters (even spaces, if escaped) and being of any
   length.  In general, though, it is usually advisable to limit array
   names to printable characters.

   The item number is the cell in which to place the new data.  It must be
   no higher than the number of the next available cell (see $numitems()
   for a trick to get this).  If the cell exists, it is overwritten.  If
   the array is to be created, the item number must be 0 (zero).  Thus,
   all array items are numbered from 0.

   The data may be anything at all.  The client will preserve the case of
   any data entered.

Returns:
   -2    could not find item number, or item number too large
   -1    could not find array, or item number not 0 for new array
    0    existing item was overwritten
    1    new array created
    2    new item number added to existing array

Examples:
   $setitem(foo 1 blah)           returns -1, no such array
   $setitem(foo 0 blah blah)      returns 1, new array created
   $setitem(foo 1 fubar booya)    returns 2, new item added
   $setitem(foo 5 booya)          returns -2, item number too large
   $setitem(foo 0 ha ha)          returns 0, item overwritten

See Also:
   Arrays(7); delitem(6); getitem(6); numitems(6)