HTML_KEEP
if (h->flags & HTML_KEEP)
h->flags |= HTML_KEEP;
if ( ! (HTML_KEEP & h->flags)) {
h->flags |= HTML_KEEP;
h->flags &= ~(HTML_KEEP | HTML_PREKEEP);
if (h->flags & HTML_KEEP && n->flags & NODE_LINE) {
h->flags &= ~HTML_KEEP;