Oh really? How do you know that the sequence of bytes http://foo.bar.com/a/c http://foo.bar.com/a/c is text or an attribute value with a regexp? How about foo

Oh really? How do you know that the sequence of bytes http://foo.bar.com/a/c http://foo.bar.com/a/c is text or an attribute value with a regexp? How about foo.bar? How about Times Roman or 16px? How about the four bytes html ?