subjh := type & tip & tope &
[FEATURE value]
"""<name lang='en'>Subject-Head Rule<EOL>
This is the description which can go across several
lines, but don't expect monospace graphics to
be preserved.
<ex>positive example
<ex>another grammatical example
<nex>ungrammatical, blocked by this type
<mex>ungrammatical example allowed by this type (mal)
<features> //(introduced by this type)
MYFEAT: does this
FEAT1: does that
FEAT2:
<notes>
blah
blah
blah
blah <ref>Pollard and Sag 1994 p67</ref>
<history>
2022-04-01 danf did something
<todo>
right node raising
<supersedes> /// one per line
subject_head
subject-head""".