<!doctype html>
<meta charset=utf-8>
<title>valid data-</title>
<!-- starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no uppercase ASCII letters -->
<p data-z="">
<!-- starts with the string "data-", has at least one character after the hyphen, is XML-compatible, and contains no uppercase ASCII letters -->
<p data-78zxyabc123-foo_bar_baz="">