*procedure
**
FINDARG
      To search for an item in a string.
      res := findarg ( keys, string )
      The string is compared with the items  in  the  string
'keys' to see if there is a match. If there is then a number
corresponding to the item in 'keys' is returned as a  result
(  first  item  being  numbered  zero  ),  otherwise  -1  is
returned.
      The    'keys'    string    should    have   the   form
"item1,item2,...,itemn".
      Examples :
      findarg ( "DP0:,DP1:,SYS:", "DP1:" )
      res <- 1
      findarg ( "DP0:,DP1:,SYS:", "FS4" )
      res <- -1


