One structural block; wordIndexes links it to its page's words list (blocks -> words only).
text is bare content for 'heading' (level separate), else the LITERAL markdown line (decoration included, round-trippable) — a pull-quote is 'paragraph', not a 5th type.
Heading level (integer 1-6); REQUIRED when type is 'heading',
FORBIDDEN otherwise — toMarkdown()/toText() validate this fail-fast (throws PdfToMdError/'ANALYSIS_INPUT'), never silently ignored.
One structural block;
wordIndexeslinks it to its page'swordslist (blocks -> words only).textis bare content for'heading'(level separate), else the LITERAL markdown line (decoration included, round-trippable) — a pull-quote is'paragraph', not a 5th type.