Binary encoded decimal instructions are part of the x86 architecture, at least from the i8086. They are similar to AAA, DAA, AAS, DAS and help to work with arithmetic operations with BCD numbers.
Here are some links to them:
https://en.wikipedia.org/wiki/Intel_BCD_opcode
According to Intel software development guidelines. These instructions are not available in long (64-bit) mode. I know, maybe the only people who really know why are designers of architecture, but why do you think they delete them?
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