[soldatoJ]

(1N)-2♣=any 2 suiter
then 2♦=relay for first suit, then 2N=relay for the second suit

it can be 4-10HCP

is it is brown sticker?

if so, is it allowed in BBO match?
normal table?
pairs?(Tournament)
IMP pairs?(Tournament)
Teammatch?(Tournament)
BBO League?(Tournament)

[helene_t]

No, at least not in the Netherlands. Any defence against 1NT is permitted. Many people play 2♦ als "multi" against 1NT, which would be a brown sticker if applied against a natural opening of 1 in a suit.

[paulg]

After a quick review of the WBF regulations this convention would not be Brown Sticker.

In the UK it would be permitted at Level 4 - most team events and serious pairs events. It is not permitted at Level 3 - most pairs events where you only play a couple of boards against a pair.

However I'd play it on BBO with no concerns at all - just alert and explain comprehensively.

For the BBO League you would need to declarer it to GOD and alert your opponents prior to the match, but otherwise would be fine.

[mikestar]

This is also ACBL General Convention Chart legal, where the only restriction on 1NT defenses is thall all direct calls other than double and 2C must have a known suit.