OULERR ( selcod, ival, string, nchars, ifail )
==============================================

  Output information about the most recent KI-error

    Can be called from the GO.

Receives:
  KI_cod_sler              *selcod         --- enquiry code

Returns:
  int                      *ival           --- integer value
  char                      string[nchars] --- null-terminated character string
 <KI_int_nchars>           *nchars         --- length of character string
                                           --- (excluding terminal null)
  KI_cod_error             *ifail          --- error code


Description:

  OULERR returns information about the most recent KI-error (ie non-zero ifail
  return from a KI routine), and is principally intended as a debugging aid to
  help pinpoint the precise cause of the error. The value of 'selcod' determines
  what information is returned :-

  +--------+-------------------+-----------------+-----------------+-----------+
  |'selcod'|   interpretation  |     'ival'      |   'string'      | max-length|
  | value  | of 'selcod' value |  return value   |  return value   | of string |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLERRO | SLER_ROutine      | KI-routine-id   | KI-routine-name |     32    |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLEREC | SLER_Error_Code   |  ifail-value    | ifail-mnemonic  |     32    |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLEREX | SLER_EXplanation  |  ifail-value    | explanation of  |    256    |
  |        |                   |                 |   error code    |           |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLERAR | SLER_ARgument     | argument number | name of faulty  |     32    |
  |        |                   | ([-1],1,2,..)   |   argument      |           |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLERAI | SLER_Array_Index  | array-index     |    null         |      1    |
  |        |                   | ([-1],0,1,..)   |                 |           |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLERLE | SLER_List_Entry   | list-entry no.  |    null         |      1    |
  |        |                   | ([-1],1,2,..)   |                 |           |
  +--------+-------------------+-----------------+-----------------+-----------+
  | SLERTG | SLER_TaG          | tag value       |    null         |      1    |
  |        |                   | [or -1]         |                 |           |
  +--------+-------------------+-----------------+-----------------+-----------+

  For codes SLERAR, SLERAI, SLERLE, SLERTG, 'ival' may be returned as (-1)
  to indicate that the enquiry is not relevant to this error (for example, the
  error may not be specific to a particular argument).

  Where 'string' is null, it will simply contain the terminal null, and the
  value of 'nchars' will be zero.