my ($request, $node); # declare two variables 
while (<DATA>) { 
	next unless /^RequestID/ or /^Nodename/; # discard useless lines 
	chomp;  # removes trailing \n 
	my($name, $id) = split /:\s+/, $_; # splits the line on colon (:) followed by any number of spaces 
	# note that ($name, $id) is not really an anonymous array, but simply a list of two fields 
	# we have two types of line, so $name may contain RequestID or Nodename, and $id contains the corresponding value 
	# the next two lines just check what there is in the first field to decide what to do with the $id value 
	$request = $id if $name eq "RequestID"; # if the line was a RequestID line... 
	$node = $id if $name eq "Nodename"; # if it was a Nonename line 
	if (defined $request and defined $node) { # the only slightly tricky part: we print the result only if we have met both types of lines 
		print "RequestID $request on nodename $node \n";	 
		($request, $node) = (undef, undef); # reset the two variables to undef to make "defined" test possible 
	} 
}