rule
dtd-start condition?
local-declaration*
action*
dtd-start is a rule performed at the start of a DTD, immediately after the document element name is
determined, so that the DTD's name is known. The built-in shelf #doctype can be used to access the DTD's
name.
The dtd-start rule allows markup comments and processing instructions prior to the DTD to be
distinguished from those within the DTD.