"The item can reference a media element in the host language or a set of
elements by the element's tag, id or class."
In SVG you might want to point out several <rect> elements for example,
they are not defined to be media elements. Please come up with another
term that can be defined by the host language.
Replace "element's tag" with "element's localName". However, these are
all just examples of what selectors can select, and this should be
clearly stated in the text, for example:
"The item can reference a media element in the host language, or a set
of elements using a CSS selector; this makes it possible to reference
elements based, for example, on the element's localName, id, or class."
"The CSS selector can match more than one element in the document host
language, for example, when CSS class selector is used. When multiple
matching occur, a sequence of elements that all match exactly the item
element is constructed. This sequence is ordered following the host
document's order and the selection mechanism will consider the elements
as ordered in such list."
What if the order changes as the result of DOM changes? What would
happen? Is the selected ordered list static or "live"? In the "host
document's order", under which circumstances is this different from
document order (depth-first pre-order traversal)? We suggest borrowing
some wording from, or normatively referencing parts of, the Selectors
API spec, http://www.w3.org/TR/selectors-api.