built-in data type
A markup-point-event triggers a rule when encountered by do markup-parse in a
markup source. It is a markup-event that does not include content, for example, a text
entity reference. A markup-point-event can be signalled as an argument of
#markup-point.
markup-point-event is an abstract type; its subtypes are used in specific contexts. For example,
markup-external-data-entity-reference-event,
markup-external-text-entity-reference-event,
markup-error-event and markup-warning-event, and
markup-processing-instruction-event.
If a markup-point-event is consumed by a do markup-parse action, it will fire a rule
of the corresponding type. The event will then be visible in the rule as #current-markup-event.