-Parsers can also target specific dialects of X·M·L, in which case they
- operate on the same basic principles as transforms (described below).
+Even when `@书社:supported-media-types` is set, it is a requirement
+ that each parser transform any `<html:script>` elements with a
+ `@type` which matches their registered types into something else.
+Otherwise the parser will be stuck in an endless loop.
+The result tree of applying the transform to the `<html:script>`
+ element will be reparsed (in case any new `<html:script>` elements
+ were added in its subtree), and a `@书社:parsed-by` attribute will be
+ added to each toplevel element in the result.
+The value of this attribute will be the value of the `<书社:id>`
+ toplevel element in the parser.
+
+It is possible for parsers to support zero plaintext types.
+This is useful when targeting specific dialects of X·M·L; parsers in
+ this sense operate on the same basic principles as transforms
+ (described below).