sub TextFile 
{
	return 0 if (! -f $_[0]);
	return 0 if (! -r $_[0]);
	
	open FH, "<" . $_[0];
	my $block = " " x 4096;
	my $bytesread = sysread FH, $block, 4096;
	close FH;
	
	if (! defined $bytesread)
	{
		print "*** ERROR: TextFile: $_[0]: $!\n";
		return 0;
	}

	return $block =~ /^[\r\n\t -~]*$/s;
}

##</code><code>##

 
$block =~ /^[\r\n\t -~]*$/s