Date:         Wed, 29 Jun 2011 03:31:21 -0400
Reply-To:     Søren Lassen <s.lassen@POST.TELE.DK>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Søren Lassen <s.lassen@POST.TELE.DK>
Subject:      Re: OT: Chance to Make SAS-L History: Did You Know That...
Content-Type: text/plain; charset=ISO-8859-1

You can use the same variable name in several IN= dataset options
in the same datastep?

Example:
  Data All_years;
    set
      xx98(in=y1998)
      mylib.t1998(in=y1998)
      otherdata
      ;
  if y1998 then year=1998;
  else year=year(saledate);
  run;

The common IN= variable will be set if one or more of the datasets
are present, meaning that
  Data out;
    merge a b(in=inx) c(in=inx);
    by ID;
    if inx then...
is equivalent to
  Data out;
    merge a b(in=inb) c(in=inc);
    by ID;
    if inb or inc then...

Regards,
Søren