Procedure SCAN( VAR Arg_string	: LINE ;
		    count	: integer ;
		VAR status	: BYTE	);
(*----------------------------------------------*)
(* version: 3.1 /8 JUN 80/ by R.E.Penley	*)
(*----------------------------------------------*
** Scan will scan your input line and return:
	STATUS:
	  0	-OK, valid inputs
	  1	-an attempt was made to exceed "count"
		 characters - so I truncated the string at
		 count chars for you.
	  2	-an invalid character was detected.
		 You figure out what to do with it!
    LENGTH(arg string) = 0 means a null string input.
**
    Valid Alphanumeric chars are the ASCII char set
    starting at the space [ CHR(32) ] and
    ending at the tilde [ CHR(126) ].
 *----------------------------------------------*
GLOBAL	StrMax = 255;
	BYTE   = 0..255;
	LINE   = STRING Default;
 *----------------------------------------------*)
VAR	loop	: (scanning, found, notfound);
	ix	: 1..StrMax;
begin
  { return status = 0 if no errors detected. }
  status := 0;
  { return status = 1 if requested length is exceeded }
  If LENGTH(arg_string) > count then
    begin
    status := 1;
    SETLENGTH(arg_string,count)
    end;
  loop := scanning;
  ix := 1;
  While (loop=scanning) do
  { return status = 2 if any invalid chars found }
    begin
    If ix > LENGTH(arg_string) then
      loop := notfound{excellent - no invalid chars}
    Else
      If arg_string[ix] IN [' '..'~'] then{good show - keep going}
	ix := SUCC(ix)
      Else
	begin
	loop := found{invalid char};
	status := 2
	end
    end{while}
End(*---of SCAN 3.1---*);
:= SUCC(ix)
      Else
	begin
	loop := found{invalid char}