A corona is actually a corona of FORMNAME. It started as
the corona of sonnets or crown of sonnets, a daisy-chain of seven Petrarchan sonnets. It has been extended so that it can apply to any fixed form. A poet could
write a corona of sheshires, or even a mixed corona having different stanzaic forms of the same line length.
The last line of one sonnet (or other form) is the first line of the next. The last line of the seventh sonnet (or other form) is the first line of the
first. The poet creates a ring or crown from the seven stanzas.