The file lao.txt was made up based on the comment in lao.el:

## ;; ISO10646's 0x0E80..0x0EDF are mapped to 0x20..0x7F.

This isn't quite right, since lao is a 94-char charset and 0x20 and 0x7F
don't exist.  So we mapped 0xE81 .. 0xEDE to 0x21 .. 0x7E.

