Backgammon Articles
What is "Nactation"?
by Tom Keith

Introduction
In their book, Backgammon Openings, Nack Ballard and Paul Weaver use a shortform notation for describing positions reached within the first few rolls of the game. They call this method of describing positions nactation, which is an amalgamation of "Nack" (for Nack Ballard) and "action notation".

Nactation works by listing the plays you make to reach the given position. Each play consists of a dice roll, given as a two-digit number, and a word describing the type of play being made (such as run, split, slot, etc.). By convention the roll is listed with the larger number first, though of course the order doesn't matter because you can play your dice in whichever order you want.

For example, suppose you win the opening with a roll of 6-4 (you roll 6, your oppenent rolls 4) and decide to run one of your back checkers from the 24-point to the 14-point. This move is described in nactation as 64-run.

Types of Plays
The following table lists the types of plays you might see and the corresponding names used in nactation.

Name Description Example
Run (R) Move one of your back checkers from the opponent's inner board to his outer board.
































Red: 63-run
Point (P) Make a point, either by moving two checkers to an unoccupied point or by adding a second checker to an existing blot.
































Red: 64-point
Down (D) Move two checkers down from your mid-point to your outer table.
































Red: 43-down
Up (U) Move both back checkers forward.
































Red: 43-up
Split (S) Move one checker up and the other checker down. In the normal split, you use the larger number to move a back checker and the smaller number to move a checker down from your mid-point. Compare this with the reverse split described below.
































Red: 43-split
Reverse Split (Z) In the reverse split, you use the smaller number to move a back checker and the larger number to move a checker down from your mid-point. To distinguish a reverse split from a normal split (above), switch the order of the dice so that the smaller number is first.
































Red: 34-split
Slot ($) Move one checker down from your mid-point and the same checker or a different checker onto a vacant point within direct range of opponent's runner on your ace-point.
































Red: 21-slot
Wild (W) Split and slot in the same move. (Write the dice roll backwards if the lower number splits and the larger number slots.)
































Red: 41-wild
Hit (H) Hit an opposing checker. This can't happen on the first roll, but it could happen on the second roll. In the example, white has opened 13/9, 6/5. Red replies 24/20*.

































Red: 31-hit

Single-Letter Nactation
You can shorten nactation to use a single letter for the type of play: R for run, P for point, D for down, etc. This makes for a convenient naming system of third-roll positions. Here is an example.

Suppose red wins the opening roll with 4-3 and splits (24/20, 13/10). White rolls 4-2 and makes his four-point (8/4, 6/4). Now red rolls 3-1.

Start:
Red rolls 4-3

























43
After red plays 43-split,
white rolls 4-2


























43S-42
After 43-split, 42-point,
red rolls 3-1































43S-42P-31

Single-letter nactation provides a short description of any opening position. It not only tells you the position, it also tells all the rolls and plays that got you there.

See:  More articles by Tom Keith

See:  Other articles on Opening Moves.

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