In Org, entry text can't have substructure (other than drawers and plain
lists): you can't have an entry that
has some text, then a subtree, then more text.
I just (re-)discovered that you can get around that by using "#+BEGIN_SRC
org" to include arbitrary org
subtrees in the middle of entry text.   That's useful not just when writing
in Org about Org, but anytime you want
to insert an extended sidenote in the middle of an entry.  As with all
source blocks, you edit it in its native (Org)
mode and it exports correctly.  You can copy links from the main Org and
past them into the nested Org.

Just wish I'd learned this sooner :)  So, maybe mention this in the manual
in the sections on drawers and plainlists.

ilya