Here is the draft language:
All undefined flags MUST be zero. Defined flags are:
First octet: 0x80 = human-readable. This note is text, a note
from one person to another, and has no
meaning to software.
My interpretation is that this is not so much a guarantee that the data
is human readable, as that it is NOT machine readable. In other words
the operational effect is that software should not try to interpret it.
It would be OK to have it be in some secret language that only one other
person could understand. So on this basis if you wanted to put a URL
in there that would be fine, setting this flag just says that software
shouldn't try to parse and understand it.
Hal