W3C validator emits warnings for LaTeXML-generated HTML5 #1016
Description
I created an HTML5 document using LaTeXML. I then ran the document through W3C's validator (https://validator.w3.org/nu/), and received the following errors and warnings:
Warning: This document appears to be written in English. Consider adding lang="en" (or variant) to the html start tag.
From line 2, column 16; to line 3, column 6
TYPE html>↩<html>↩<head
The following is odd because LaTeXML-html5.xsl contains 'omit-xml-declaration="yes"':
Error: Saw <?. Probable cause: Attempt to use an XML processing instruction in HTML. (XML processing instructions are not supported in HTML.)
At line 1, column 2
<?xml version="1
The following results from the down-arrow download link LaTeXML adds to lstlisting environments:
Error: Bad value for attribute href on element a: Illegal character in scheme data: line break is not allowed.
From line 176, column 158; to line 176, column 787
ing_data"><a href="data:text/plain;base64,Li9zY3JpcHRzL2ZlZWRzIGluc3RhbGwgY2EtY2VydGlmaWNhdGVzIFwKICAgICAgICAg…ICAgIHpvbmVpbmZvLWNvcmUgXAogICAgICAgICAgICAgICAgICAgICAgICB6b25l aW5mby1ub3J0aGFtZXJpY2E= ">⬇</a><