-By default, ⛩️📰 书社 installs files to the same location in `DESTDIR`
- as they were placed in their `SRCDIR`.
-This behaviour can be customized by setting the `@书社:destination`
- attribute on the root element, whose value can give a different path.
-This attribute is read after parsing, but before transformation (where
- it is silently dropped).
+⛩📰 书社 will add a few attributes to toplevel result elements, both
+ in the main document and any embedded documents, during the expansion
+ phase prior to the main transformation.
+These include :—
+
+- A `@书社:cksum` attribute giving the `cksum` checksum of the
+ corresponding source file.
+
+- A `@书社:mtime` attribute giving the last modified time of the
+ corresponding source file.
+
+- A `@书社:identifier` attribute giving the ⛩📰 书社 identifier
+ (i·e, starting with `about:shushe?`) of the corresponding source
+ file.
+
+- For elements in the `html` namespace, an `itemscope` attribute and an
+ `itemtype` attribute with a value of
+ `urn:fdc:ladys.computer:20231231:Shu1She4:document` (for the main
+ document) or `urn:fdc:ladys.computer:20231231:Shu1She4:embed` (for
+ embedded documents).
+ These attributes are used to scope any nested `<html:meta>` elements
+ with `@itemprop` attributes to their containing documents.