TRICK 2.--Z infers that the adversaries will not continue with
the spade suit as Y holds a tenace over A’s cards. Every suit is
protected, but it would be dangerous to have clubs led through, for,
should A obtain the lead, this entire suit might be brought in. In
all probability the adversaries will make a trick in diamonds and Z
prefers that the first be taken by B.
TRICK 3.--B leads an irregular card in hearts so that A can mark his
suit. Z cannot afford to have A lead and so takes this trick.