[SGF FF[4] - Smart Game Format]

Go (GM[1])

Move, Point & Stone type

In Go the Stone becomes Point and
the Move and Point type are the same: two lowercase letters.
[coordinates (TA2.gif)] Coordinate system for points and moves
The first letter designates the column (left to right), the second the row (top to bottom). The upper left part of the board is used for smaller boards, e.g. letters "a"-"m" for 13*13.
A pass move is shown as '[]' or alternatively as '[tt]' (only for boards <= 19x19), i.e. applications should be able to deal with both representations. '[tt]' is kept for compatibility with FF[3].
Using lowercase letters only the maximum board size is 26x26.
In FF[4] it is possible to specify board sizes upto 52x52. In this case uppercase letters are used to represent points from 27-52, i.e. 'a'=1 ... 'z'=26 , 'A'=27 ... 'Z'=52

How to execute a move

When a B (resp. W) property is encountered, a stone of that color is placed on the given position (no matter what was there before).
Then the application should check any W (resp. B) groups that are adjacent to the stone just placed. If they have no liberties they should be removed and the prisoner count increased accordingly.
Lastly, the B (resp. W) group that the newest stone belongs to should be checked for liberties, and if it has no liberties, it should be removed (suicide) and the prisoner count increased accordingly.
See also: extensive explanation with examples (should leave no question unanswered; is part of FF5 discussion but valid for FF4 as well).

Properties

TW and TB points must be unique, i.e. it's illegal to list the same point in TB and TW within the same node.
Property:	HA
Propvalue:	number
Propertytype:	game-info
Function:	Defines the number of handicap stones (>=2).
		If there is a handicap, the position should be set up with
		AB within the same node.
		HA itself doesn't add any stones to the board, nor does
		it imply any particular way of placing the handicap stones.
Related:	KM, RE, RU

Property:	KM
Propvalue:	real
Propertytype:	game-info
Function:	Defines the komi.
Related:	HA, RE, RU

Property:	TB
Propvalue:	elist of point
Propertytype:	-
Function:	Specifies the black territory or area (depends on
		rule set used).
		Points must be unique.
Related:	TW

Property:	TW
Propvalue:	elist of point
Propertytype:	-
Function:	Specifies the white territory or area (depends on
		rule set used).
		Points must be unique.
Related:	TB