begin
comment set two neighbor bits to 00;
	bits bt, b2;
	integer n;
	n := 7;
	bt := #12ab34cd;
	write(bt);
	b2 := #3; comment two bits;
	b2 := b2 shl n;  b2 := ~b2;
	bt := bt and b2;
	write(bt);
end.