Data files containing cross sections can be subsetted by controlling which cross sections to include in the output data set. Selecting a subset of cross sections is accomplished using the WHERE statement. The WHERE statement gives a condition that the BY variables must satisfy for a cross section to be selected. For example, the following statements extract the monthly market rate conversion factors for the United Kingdom (COUNTRY=’112’) and Switzerland (COUNTRY=’146’) for the period from September 1985 to February 1986.

   filename datafile "imfifs1.dat" RECFM=F LRECL=88;
   
   title3 'Time Series Defined in Selected Cross Sections';
   proc datasource filetype=imfifsp
      outselect=on ebcdic
      interval=month
      out=ifs;
   
      where country in ('146', '112') and partner=' ';
      keep F___AA F___AC;
      range from '01sep85'd to '01feb86'd;
   run;
   
   title4 'OUTALL=IFS Data Set';
   proc print
      data=ifs;
   run;