[zenko]

In most systems if bidding goes 1x-DBL-p-1y-p-2y is at least somewhat invitational (depending on style). Does anything change if bidding goes 1x-DBL-1z-1y-p-2y? Doubler's partner bid freely, does that change the nature of doubler's raise to mere courtesy raise, or it still has invitational overtones? Also sequence p-p-1x-p-1y-p-2y probably belongs into same category.

In both cases my tendency is to always raise if I have 4 card support, even with absolute trash, so if I do not raise I deny 4 card support, but I am not sure can I expect an expert partner to expect that.

[ArtK78]

The "standard" or "old-fashioned" treatment of a raise by the takeout doubler is that it shows extra values, as there is no need to bid his values twice. The takeout double already showed an opening bid with support for the unbid suits, so any further action taken by the takeout doubler shows extras.

The more modern trend is for the takeout doubler to raise without showing extras so as to make it harder for the opponents to compete. This is more true when there is an opponent's bid after responder's bid (before the takeout doubler).

I don't believe that a bid immediately after the takeout double changes anything other than the fact that the takeout doubler knows that his partner has values for his bid.

My personal preference is to have a partnership agreement mandating a raise with 4 card support, so a raise shows no extras but a failure to raise shows fewer than 4 cards in support (and, of course, the inability to make any other bid which would show extras).