1. This is one of the few rules from the UK to have hyperbolic log scales.
2. As with other hyperbolic rules I have seen sinh is covered by two scales, 0.1 to 0.9 and 0.9 to 3.0. Tanh is covered by one scale from .1 to 3. The value of x is entered on the appropriate scale and the value of the function is read on the D scale. This range is common as below 0.1, sinhx » x , and above 3.0, sinh »  e^x . Similarly below 0.1, tanh x » x and above 3.0,  tanh x » 1.
3. The rule has a full complement of folded scales (DF, CF etc) and inverse scales including the rather uncommon DI.