Footnotes:

1) T-card names may not be made up of only hexadecimal characters, as
   they would be indistinguishable from a hash prefix.

2) Tags in [#ctrl | Control Artifacts] may not be
   self-referential. i.e. they may not start with <tt>*</tt>.
   self-referential. i.e. their target hash may not be <tt>*</tt>.

3) Tags in [#event | Technotes] must be self-referential. i.e. their
   target hash must be <tt>*</tt>. Similarly, technote tags may only
   be non-propagating "add" tags. i.e. their name prefix must be
   <tt>+</tt>.

4) [#forum | Forum Posts] must have either one H-card or one
   I-card, not both.

5) [#forum | Forum Post] P-cards must have only a single parent
5) [#forum | Forum Post] P-cards may have only a single parent
   hash. i.e. they may not have merge parents.

<a id="addenda"></a>
<h2>4.0 Addenda</h2>

This section contains additional information which may be useful when
implementing algorithms described above.