It must be one of the following characters (not case-sensitive):
 
   N - no EXEC SQL support is present 
   Y - the user has provided for EXEC SQL support by an 
       explicit PREPROCESS directive or the SQL directive. 
   X - the XDB EXEC SQL preprocessor is to be invoked by 
       the TX preprocessor 
   G - the GUPTA EXEC SQL preprocessor is to be invoked by 
       the TX preprocessor 
   0 - not specified