A MARKUP-REGION-EVENT was left unclosed. The innermost unclosed event is 'X'.
The end of a MARKUP-REGION-EVENT does not have a corresponding start. The event is 'X'.
Encountered the end of MARKUP-REGION-EVENT 'X' when the last started region is 'Y'.
The MARKUP-REGION-EVENT 'X' appears more than once.
where X and Y are descriptions of markup events.
#markup-endsignal must be preceded by a
#markup-startsignal with the same (reference-equal)
markup-region-eventargument in the same stream, and vice versa: every
#markup-startmust be followed by the corresponding
#markup-endbefore the end of the markup stream.
#markup-endsignals must be properly nested.
#markup-startsignals using the same
markup-region-eventargument, there must be a
#markup-endwith the same argument between them. In other words, a region cannot be restarted without being ended first. The opposite rule also holds: two
#markup-endsignals with the same event must be separated by a
#markup-start, so no region can be ended twice.