I just stumbled across this post, but it is a topic I have researched twice in the last few years, with unsatisfactory results. Unofficially, I recommend placing a dot 6 before each numeric indicator. The only approximate matches in the existing UEB character set are four Early English letters, but in each case the cell following the dots 3456 is NOT a-h.
Creating a UEB symbol this way is not valid, but certainly is far more efficient than the only legitimate UEB symbol. I believe I will continue using this technique as long as no other efficient sign is officially endorsed.