The complex parsing algorithm wasn't spelled out in excruciating detail, as it is in HTML5; much of it was implied, and left for the parser developers to figure out.
Strictly, the HTML, HEAD, and (BODY|FRAMESET) elements are required, in a valid document, but the tags delimiting them are optional. That way, code which manipulates the DOM can always count on a HEAD element being present, and CSS specifiers can use 'body' as a root, even if the tags themselves are missing from the source HTML file.
The first actual required tag in an HTML 4 document is <title>, as far as I know. Every HTML document has to have one, and it needs to be opened and closed explicitly. If it's the first thing in the document, it implies an <html><head> before it, and if body content comes after it, that will imply </head><body> as well.
You could put a <meta> tag anywhere before the first body content, and it would still be part of the implied HEAD element. As long as it doesn't come after the (explicit or implicit) </head> tag, it shouldn't cause the document to fail validation.
And no, none of this is valid XHTML. XHTML is always strict, and all opening and closing (or self-closing) tags must be present in the source file.
The complex parsing algorithm wasn't spelled out in excruciating detail, as it is in HTML5; much of it was implied, and left for the parser developers to figure out.
Strictly, the HTML, HEAD, and (BODY|FRAMESET) elements are required, in a valid document, but the tags delimiting them are optional. That way, code which manipulates the DOM can always count on a HEAD element being present, and CSS specifiers can use 'body' as a root, even if the tags themselves are missing from the source HTML file.
The first actual required tag in an HTML 4 document is <title>, as far as I know. Every HTML document has to have one, and it needs to be opened and closed explicitly. If it's the first thing in the document, it implies an <html><head> before it, and if body content comes after it, that will imply </head><body> as well.
You could put a <meta> tag anywhere before the first body content, and it would still be part of the implied HEAD element. As long as it doesn't come after the (explicit or implicit) </head> tag, it shouldn't cause the document to fail validation.
And no, none of this is valid XHTML. XHTML is always strict, and all opening and closing (or self-closing) tags must be present in the source file.