Like with the style, options defined on the doctitle are not available in the parsed document. Assembler should provide the `assembly-opts` that works similarly to `assembly-style` attribute to carry over options from the doctitle to the section title it becomes in the assembly. Alternately, Assembler could look for shorthand options above the doctitle in the AsciiDoc source and preserve them. This might make sense since `opts=unbreakable` already works.