After we've loaded the high part of the core words, we're at
the "wrapping up" part. We add what we call a "hook word" (an
empty word with a single letter name) which doesn't cost us
much and can be very useful if we need to augment the binary
with more words, and at that point we have our future boot
CURRENT, which PC yields. That is why we write it to the
LATEST field of the stable ABI: This value will be used at
boot.

After the last word of the dictionary comes the "source init"
part. The boot sequence is designed to interpret whatever comes
after LATEST as Forth source, and this, until it reads ASCII
EOT character (4). This is generally used for driver init.

Good luck!