The documentation says that \dXXX has only an option argument and \cXXX an optional argument and a mandatory argument for the value but actually it is the other way round:
(it would be good if there were some mnemonic for the naming. I personally would prefer e.g. \cvXXX (currency value) or \nXXX (\n for number) or \vXXX (\v for value) for the variant with a value.)
The documentation says that \dXXX has only an option argument and \cXXX an optional argument and a mandatory argument for the value but actually it is the other way round:
(it would be good if there were some mnemonic for the naming. I personally would prefer e.g. \cvXXX (currency value) or \nXXX (\n for number) or \vXXX (\v for value) for the variant with a value.)