Would the following 1D opening be GCC legal:
8-11 hcp, balanced or 5422, 3+ diamonds.
- The ACBL has exercised its right under L40D to ban one level openings with fewer than 8 HCP (ok, so its conversion from "a king below average" to "7HCP" is arguable, but you're not going to get much sympathy from anyone).
- Apart from the above, any natural 1 opening is legal, as is any other meaning provided the call guarantees 10 HCP.
- While 3 diamonds is considered "natural" for a 1 call, adding on the restrictions that the hand must be balanced and so very limited in strength makes this arguably "artificial". I am sure that somebody will make this argument, which if they were successful would make it illegal, as it does not guarantee 10 HCP.
- If, however, 1 was "natural with diamonds (I would guess 4+ here, given my guesses as to the rest of the system) or 8-11 balanced or 5422, 3+", you are more likely to be ok, especially in the context of a light opening system, where you open most 8 counts, not just the balanced ones.
- If this is not judged GCC legal, it won't be Mid-chart legal, either.
I guess what I'm saying is "maybe, depending on what the rest of the system looks like, what the directors at the table think, and how nice a person you are." I will warn you that when you reach the boundaries of the GCC, many players and some TDs will be looking for ways to rule you over the edge, and the line between "natural" and "artificial" (and "conventional" and "non-conventional" - those two pairs, especially when connected to the GCC, are not quite equivalent)
David is, of course, correct that we in the ACBL, with all our faults, do not use the concept of "opening points" - at least, not in our regulations. We use the more-useful hand evaluation tool of Work-count HCP, because adding three numbers is too complicated for most of the ACBL members. (this is a joke, friends).
I would strongly suggest you send a more detailed system summary to firstname.lastname@example.org and see what they say.