From memory the rules says "a contacting, contacted or TZed element".
[it] ... from which the question, since asked, is whether "contact" as it pertains to EMTLU is instantaneous or continuous (cf brilliant stroke +2 vis-a-vis all generals' +1 in tactical factors). The inference that some have drawn is that it is the former, ie you can use EMTLU at the instant of contact with the enemy of crossing the boundary of an enemy TZ but not subsequently with respect to the same contact or TZ. I can't say for certain - is there a grammarian in the house? I can see all sorts of "interesting" rationalisations emerging for one determination or the other
In the example quoted there is a relevant section on P33, para 2 that states that an element initiates close combat by adjusting an existing flank contact. I guess the question is, then, does such a move, partial flank contact to (i) mutual front corner contact or (ii) front edge contact with the enemy elements full flank edge cost 0, 1 or, if irregular, 2 PIPs?
