/usr/share/doc/axiom-doc/bitmaps/surd.bitmap is in axiom-hypertex-data 20170501-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 | #define surd_width 16
#define surd_height 16
#define surd_x_hot -1
#define surd_y_hot -1
static char surd_bits[] = {
0x00, 0x00, 0x00, 0x60, 0x00, 0x30, 0x00, 0x10, 0x00, 0x18, 0x00, 0x08,
0x00, 0x0c, 0x00, 0x04, 0x00, 0x06, 0x07, 0x02, 0x04, 0x03, 0x0c, 0x01,
0x98, 0x01, 0x90, 0x00, 0xf0, 0x00, 0x60, 0x00};
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