Layer number found in the upper right corner of the board
Layer number found on the second side.
Found etched into the top layer in the bottom right corner of the board on both sides.
Found etched into each corner on the front and back.
overall: 25 in x 24 5/8 in x 1/4 in
The record contains a 24 layer back plane with 10 signal layers, one clock layer, 11 reference layers, and two pad layers. Each side appears to be identical with a four by four array of 5 3/8 inch square connector pads and a row of rectangular socket pads. The whole board is covered with a stagared checker board array.