-/*
- * Simplified grammar of syntax tree:
- *
- * MDOC_ROOT: root of tree
- * MDOC_TEXT: free-form text
- * MDOC_ELEM: elem [args] MDOC_TEXT...
- * MDOC_BLOCK, MDOC_HEAD, MDOC_BODY, MDOC_TAIL:
- * MDOC_BLOCK:
- * MDOC_HEAD [args] (MDOC_TEXT|MDOC_ELEM|MDOC_BLOCK)...
- * MDOC_BODY (MDOC_TEXT|MDOC_ELEM|MDOC_BLOCK)...
- * MDOC_TAIL (optional) (MDOC_TEXT|MDOC_ELEM|MDOC_BLOCK)...
- */
-