Let's try this on for size (pun?):
A body part has several levels of context, or interpretation. In
theory, the number of levels might get quite large, and our attempting to
handle the theoretical maximum, or the possibility of infinite nesting,
will bog us down. But just for the heck of it, let's try the following:
1. How I, the sender, want it interpreted; e.g., run the BP through
a program that is located in file foo/bar
2. BP consists of data generically characterized in a standard
category, and precisely defined by a simple citation
3. Data are being sent according to a cited encoding standard.
Hence, there is the sender's view, the 'byte' (or thereabouts) view of
the interpretable data, and finally the transmission convention.
So, I might have
3. Quoted Text