additional @file{viewer/}). Under either name, the schema URIs are
not resolvable to obtain the schemas themselves.
-One may ignore all of the above in interpreting a structure member.
+@c XXX The namespaces are important for writing SPV files, so we
+@c should note them.
+
+One may ignore all of the above in interpreting a structure member.p
The actual XML has a simple and straightforward form that does not
require a reader to take schemas or namespaces into account. A
structure member's root is @code{heading} element, which contains