I haven't been able to figure out just what these guys are trying to report: for example is Nim S Cu: Nimbus, Stratus, Cumulus; Nimbostratus and Cumulus; or, Nimbus and Stratocumulus? Similarly for other combinations of clouds. Sometimes they write one or two cloud types above another one in the same box. Do they do that because of space limitations, or is it significant? After trying, in vain, to sort it out, I concluded that each person was doing his own thing and not following any strict rule, and so the cloud types are, generally speaking, not very useful. So, on any day Ci Cu could be Cirrus and Cumulus, or Cirrocumulus or some other cloud type altogether.
Although I don't know, I suspect that Philip doesn't worry about matching the cloud codes.