For my understanding, I think it can be an confirmation that if the next CV after the current 003 is identical to be around the same tonnage, CATOBAR and conventional powered.
- If it is named 004, then the number is just sequence.
- If it is named 003, then it is type number.
It may be named 004, but it can also be of Type 003 simultaneously, with 003 being the first ship of the class. This is the USN convention anyway.