Laocoon166, on 2014-April-28, 17:33, said:
I think he's referring to Law 73D:
Quote
- It is desirable, though not always required, for players to maintain steady tempo and unvarying manner. However, players should be particularly careful when variations may work to the benefit of their side. Otherwise, unintentionally to vary the tempo or manner in which a call or play is made is not in itself an infraction. Inferences from such variation may appropriately be drawn only by an opponent, and at his own risk.
- A player may not attempt to mislead an opponent by means of remark or gesture, by the haste or hesitancy of a call or play (as in hesitating before playing a singleton), the manner in which a call or play is made or by any purposeful deviation from correct procedure.
Misleading this way is not usually classed as MI, but he's right that you're not supposed to do it.