CAT023 is the catalog number (and the unofficial name) for the perhaps most sought-after Richard D. James recording ever. It was printed in the early nineties on only 4 copies of vinyl, three of which were given to friends of Richard D. James. Thus, the persons in posession of this record are: Mike Paradinas (ยต-Ziq), Chris Jeffs (Cylob), Grant Wilson-Claridge (co-founder of Rephlex Records) and Richard D. James (Aphex Twin)
The tracklisting is unknown, but an interview with a certain Bowgie (rumors say that this is actually Mike Paradinas - he did post on the messageboard there for a period around 2000), performed at www.joyrex.com on September 14, 1999 tells us a bit about the album. I have reproduced the entries as-is (including typos from the original source). According to Bowgie, the labels are handwritten with black marker.
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Side A
Label: "CAUSTIC WINDOW LP 33 1/3 SIDE A REPHLEX"
Run-out groove: "CAT 023-A1 A PORKY PRIME CUT"
A1: Untitled
[Track 1] is a subtle melodic grower, with hi q's; pianoish DX sounds & woodwind type synths.nice but not very immediate.
A2: Untitled
Track 2 is *much* more like it: Industrial type drums straight out of J5 and the catchiest afx acid line (not 303). Builds and builds with pad sounds & percessive held chords in a spooky fashion.
http://www.youtube.com/watch?v=7iZ6t-9USa0