Right now, our implementation will only match date skeletons that are an exact match of what's in CLDR. We should at least do the somewhat "safe" extension of including a MMMM format ( long month name ) whenever we find a MMM format ( abbreviated month name ) in the CLDR data, assuming that an explicit MMMM format does not exist. There are some locales in CLDR where it does indeed exist.
Right now, our implementation will only match date skeletons that are an exact match of what's in CLDR. We should at least do the somewhat "safe" extension of including a MMMM format ( long month name ) whenever we find a MMM format ( abbreviated month name ) in the CLDR data, assuming that an explicit MMMM format does not exist. There are some locales in CLDR where it does indeed exist.