This string is the startup banner for HOL Light, and is displayed when
standalone images (see self_destruct) are started up. It is only available
in HOL images created using checkpointing (as in the default Linux build
arising from make all), not when the HOL Light sources have simply been
loaded into the OCaml toplevel without checkpointing.
On my home computer, the value is currently:
val it : string =
" HOL Light 2.10, built 16 March 2006 on OCaml 3.08.3"