Update to the system I'm designing for mid-chart (ACBL convention chart) pairs:

Note: N12 = Not vulnerable in 1st/2nd, V34 = Vulnerable or 3rd/4th

1C: Big, 18+ or 15-17 with playing value, either:
1) 15-17 unbalanced, a 6+ suit or a 5-4-3-1 or a 5-5
2) 18+ any

1D: Mini catch-all, 10-14, 3-4Ss V34, 2-4Ss N12, no six card suit, not 5-5, if balanced 11-12 V34, 13-14 N12 or 12 with 4cM or 5Hs

1H: 15-17, balanced or semi-balanced. Can have a five card major or six card minor. Can be any 4-4-4-1. Not a 5-4-3-1 unless singleton is A, K, or Q.

1S: 9-14, 5+Ss

1NT: Balanced including 5-4-2-2s without 5Ss. 12-14 V34 (12 with 3-4Ss can optionally open 1D), 10-12 N12 (no 4cM or 5Hs if 12). Not 5Ss.

2C: 5+Cs, 10-14, if just 5Cs must have a singleton/void S.

2D: 5+Ds, 10-14, if just 5Ds must have a singleton/void S and/or be 5-5 in the minors.

2H: 5+Hs, 10-14, if just 5Hs must have a singleton/void S and/or be 5-5 with a minor.

2S: 5-9, 5+Ss

2NT: 6-5/5-6+ in majors, 10-14

Since almost all 10 counts are opened N12, for not vulerable 34 (N34), 1NT should be 12-15 (a major only if 12-13 and optional), and the balanced range in 1D should be 12-15. 1H will be 15/16-17 balanced, 15s with a five card suit.

1NT in N12 should include the dismal 13s - the 3-3-3-4 and 3-3-4-3 hands.