In XHTML 1.0 Strict do attribute values need to be surrounded with quotes?

Question

In XHTML 1.0 Strict do attribute values need to be surrounded with quotes?

Example:

A

Answer 1

Yes, all attributes must be quoted, and yes, attributes can use single or double quotes. Just be consistant—don't open an attribute with a single quote and close with a double quote. And also, you should leave a space between the closing slash and the last attribute of self-closing tags, to keep compatibility with old browsers, as so: