The contents page of SFG20 published by BESA has New Rules of Measurement 3 codes. But these codes in many cases extend NRM3 beyond the fifth level to a sixth, breaking down as required often to to give mapping to SFG20.
One could construct a table yourself from those contents & SFG20 titles, to extend the logic tables published by RICS but can it be obtained, even paid?
Uniclass System (Ss) table mappings if poss, and Product (Pr) if anyone has them too.