Brozel:/Pinpoint Astro

X = 1-suited hand, any suit. Advancer bids 2C to find out. Some require a good suit to double, so that advancer can leave the double in with a fair balanced hand.

2m = m and H, at least 5-4 in the two suits
2H = majors
2S = spades and a mystery minor (bid 2N to find out which)
2N = minors

Some use 3-level bids as natural, showing a longer suit than the double, while some use it to show a 3-suiter with a singleton or void in the bid suit.