STR$POSITION

   The Return Relative Position of Substring routine searches for
   the first occurrence of a single substring within a source
   string. If STR$POSITION finds the substring, it returns the
   relative position of that substring. If the substring is not
   found, STR$POSITION returns a zero.

   Format

     STR$POSITION  source-string ,substring [,start-position]
 

Additional information available:

Corresponding_JSB_Entry_Point   Returns         Arguments