To whomever asked whether you could write "binary" literals in a binary radix, yes, it turns out you can. The default radix for display is hex, but you can write the literals in base-2, 16, or 64:
>> #{A9B4}
== #{A9B4}
>> 2#{10110010}
== #{B2}
>> 16#{A9B4}
== #{A9B4}
>> 64#{GNhcm5hb}
== #{18D85C9B985B}
No octal, apparently.
Here's a thorough tutorial on REBOL:
http://www.re-bol.com/rebol.html
The main REBOL site also has some very nice docs:
http://www.rebol.com/r3/docs/index.html
Enjoy!
- Lyle