You wouldn't have two or more reference compilers -- that would defeat the point. There are three popular D compilers, one of which (DMD) can be considered the

You wouldn't have two or more reference compilers -- that would defeat the point. There are three popular D compilers, one of which (DMD) can be considered the reference. As for "reference manual" -- well, every tool should have a reference manual. The "reference" here has a different connotation. I think you might be conflating "reference manual" with "formal specification", which is not accurate in this case (and in most cases).