@@ -514,6 +514,36 @@ delimiter
514514: delimiter of list numbers; one of `DeaultDelim`, `Period`,
515515 `OneParen`, and `TwoParens` (string)
516516
517+## Hierarchical Element {#Element}
518+
519+Hierarchical elements can be either *Sec* (sections) or *Blk*
520+(blocks). *Blk* elements are treated like [block]s.
521+
522+### Sec
523+
524+Section elements used to provide hierarchical information on
525+document contents.
526+
527+**Objects of this type are read-only.***
528+
529+level
530+: header level (integer)
531+
532+numbering
533+: section numbering ([list] of integers)
534+
535+attr
536+: header attributes ([attributes])
537+
538+label
539+: header content ([list] of [inlines])
540+
541+contents
542+: list of contents in this section ([list] of hierarchical elements)
543+
544+t, tag
545+: constant `Sec` (string)
546+
517547
518548[block]: #block
519549[blocks]: #block