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| 64S-43Z-63 | |
Mike has tables to neatly display the families and their attributes in detail, and sometimes cross-references with links better, but here are my answers:
The S (Split) family: Play the big number on the far side and play the small number "down" in the restricted sense, from far outer board to near outer board. There is only one S-family play, which is S = 24/18 13/10, as you correctly guessed.
The Z (reverse split) family: Same as the S family (above) except the words "big" and "small" are reversed. Z = 18/15/9.
Note that I wrote "18/15/9" instead of 18/9. That was just to clarify the move portions. The 3 is played on the far side and the 6 is played down from the far outer board to the near outer board.
[For reference, the second- and third-ranked Z-family plays in this position are: z = 18/15 13/7, and Z = 24/21 13/7.]
Instead of Z, you may nactate 18/9 with a lower case "p." Making the 3pt (9/3 6/3) is P; when points are equidistant from the 6pt the lower point gets the (higher ranked) capital letter.
A third way to nactate 18/9 is with the numeral 9. Whether you choose Z, p or 9 is largely a matter of personal preference.
9/3 6/3 can be nactated with either P (Point) or A. The buzz word for A is "Attack," but the defintion is to play half the move by jumping over the bar (from outer board to inner board) and the other half within the inner board. Yet another choice for 9/3 6/3 is numeral 3.
You are correct that R (Run) = 24/15. R-family plays are confined entirely to the far side of the board.
Finally, you are correct that C (Cross) = 24/18 9/6. [For reference, c = 24/18 8/5, C = 18/15 9/3, and c = 18/15 8/2.] You could also use T (sTack/Tower) or numeral 6 for this play.
The definition of I has been changed from the old tutorial. It now means to play the entire move Inside (within the inner board). There is no I play in this position because the 6 does not originate from inside -- it cannot be legally played within the inner board.
Thanks to the hit/more/6 rule, just using the correct family will allow you to successfully nactate 95+% of backgammon plays. Either you'll be exactly right or the reader will correctly assume your intention because there is no other play in that family that is nearly as strong. The case of P and p in this position is an exception, but if you notice a seeming ambiguity and are unsure how to apply the hit/more/6 rule, there is usually an alternative character to bail you out (in this case, Z or 9).
Nack