private boolean parseProlog() throws Exception {
        parseMisc();

        if (tryRead("<!DOCTYPE")) {
            parseDoctypedecl();
            parseMisc();
            return true;
        }
        return false;
    }
Parse the prolog of an XML document.

<pre>
 [22] prolog ::= XMLDecl? Misc* (Doctypedecl Misc*)?
</pre>

<p>
We do not look for the XML declaration here, because it was handled by
pushURL ().

@see pushURL
@return true if a DTD was read.
src/nu/validator/gnu/xml/aelfred2/XmlParser.java