I'm curious about a very old Chinese go book that is the subject of this Sensei's Library page:
http://senseis.xmp.net/?WangyouQingleJi

Wangyou Qingle Ji
忘憂清樂集

I believe it is also called "Carefree & Innocent Pastime" in English discussion

Does anyone know if photographs of it can be found online somewhere? Or is anyone here at least familiar with it?

In particular, I'm interested in its diagrams and conventions. Another Sensei's Library page mentions that it uses a coordinate system that is very similar to Audouard's coordinate system (http://senseis.xmp.net/?AudouardCoordinates), and I would like to know more about whether or not that is the case.

The coordinate system used in ancient China resembles a clockwise rotation and the four quadrants are named as either the four seasons or the four tones (ping, shang, qu, ru). You may say that it is very similar to Audouard's coordinate system, although the latter came a thousand years later.

Ruoshi Sun, thanks for the reply! I'm very curious about this ancient coordinate system. Do you happen to know of any resources (books, websites, SL posts) that discusses it further? This system seems to have faded into obscurity. I wonder how and why that happened.

If you can read Chinese, this should suffice:
http://zh.wikipedia.org/wiki/%E5%9B%B4% ... 1.E6.B3.95

The quote from Wang You Qing Le Ji says, "The go board contains 361 points. The characters ping, shang, qu, ru (four tones) are used to describe each quadrant, which contains 90 points. The left hand side of the go board is honorable, and thus designated as ping. In the clockwise direction, [the coordinate] begins at 1 and ends at 10. In the counterclockwise direction, [the coordinate] ends at 9. If one says '6-3', first count 6 in the clockwise direction, and then 3 in the counterclockwise direction. If one says '3-6', first count 3 in the clockwise direction, and then 6 in the counterclockwise direction."

The second quote is from Shi Xiangxia's book Yi Li Zhi Gui. To paraphrase, it adds that the coordinates are always "first vertical then horizontal", as in the ping (bottom left) and qu (upper right) quadrants, and moving to the shang (upper left) and ru (bottom right) quadrants, the vertical and horizontal axes are flipped, which is due to the clockwise rotation.

This system preserves the mirror and rotational symmetry of the go board, but requires 3 numbers to describe a coordinate (quadrant, vertical, horizontal) and also the knowledge of clockwise motion, but of course in 2D space one really only needs 2 numbers (cartesian). So the former is more cumbersome and can potentially cause more confusion. However, note that in daily conversations we still say "4-4 point at the upper right corner" instead of "16-16 point", but that we cannot distinguish between 3-4 and 4-3 anymore.

YeGo:

I haven't got a scan of the pages of C&IP explaining the coordinate system handy, and I'm not willing to dig out the materials, I'm afraid, but I have the attached a few images on file (from a paper I presented on the history of go publishing) and they will explain a few things.

The first diagram shows a clumsy attempt by me to render the system in a modern way. The original shows every point marked.

The second diagram is a famous problem (Gaozu Relieves the Siege of Yingyang: White to play and live), with the solution. The solution is a sequence of moves on a 4x10x9 grid system, plus (optional) technical terms for each move. The solution starts in the black cartouche on the second line from the right and the first character　去 denotes the quadrant. Thereafter there is no need to repeat that and the subsequent format is e.g. "26 connects" (note they wrote 26 for 2-6).

C&IP also used a format more familiar to us, as in the third diagram, which shows a joseki variation (using Chinese numerals, of course).

The quadrant system was used up until modern times, for example in the commentaries by Xu Xingyou. Very often the quadrant was not specified at all - good players were assumed to apply their common sense, though once in a while there are cases of genuine confusion. Since commentators tended to denote moves in terms of move numbers (e.g. "Black 54 ought to have been at 175") there was also potential for confusion between the two systems within commentaries, and (if the quadrant marker was omitted) this was obviated by using the suffix 路　for empty points using the quadrant numbers and 位 for points occupied by numbered moves, in the same way that we distinguish A19 and move 123.

The name C&IP is due to me.

John and Ruoshi, thank you for the elaborating posts.

Quite interesting that CI&P uses a rotational convention for the order of the coordinates. So, it's effectively column-row for the upper-left and bottom-right corners, but row-column for the upper-right and bottom-left corners.

I didn't realize that corner-relative systems were used up until modern times.

I think I read somewhere (although I don't remember the source) that the A19 system used for go was influenced by the system used for chess, which shows from the borrowed conventions of placing A1 in the bottom-left, specifying columns with letters and rows with numbers, and giving the column coordinate first.

Ruoshi, you mentioned that 3 characters are necessary for a corner-relative system, however, two characters are sufficient (if the character itself disambiguates which edge is being counted from). I proposed such a system in this thread:
viewtopic.php?p=184072#p184072