Boost.Decimal has the following statement in the front matter of its documentation.
Boost.Decimal is an implementation of IEEE 754 and ISO/IEC DTR 24733 Decimal Floating Point numbers.
It looks like conscious decisions were made to depart from both IEEE 754 and ISO/IEC DTR 24733 where the full conformance is deemed impractical. This decision seems the right thing to do, but it *HAS TO* be reflected in the docs. Either list all the aspects where you depart from the two standards, or say up front that the library is just "inspired" by those standards.
I think the best move here is to add deviations into the design decisions page which becomes "Design Decisions and Standards Deviations". Right now there are some, but not all, that are sprinkled throughout the documentation. The could all be consolidated in one place, since the rationales for deviations are design decisions. An example is at the top of the <cmath> page it talks about none of the functions actually meet the IEEE standard of 0.5 ULP precision since this is an unreasonable expectation [1]. Matt [1] https://develop.decimal.cpp.al/decimal/cmath.html