The Latin alphabet of the time still lacked the letters ⟨j⟩ and ⟨w⟩, and there was no ⟨v⟩ as distinct from ⟨u⟩; moreover native Old English spellings did not use ⟨k⟩, ⟨q⟩ or ⟨z⟩. What was the term for the letter ƿ?