Interpreting reference numbers on trade patches

[DougSA]

Can anyone shed light on the different sequences of reference numbers used on Royal Navy trade patches? I am assuming that there has been a standard list of reference numbers at any particular point in time, which has been updated periodically over the years.

I am attaching pictures of some trade patches, of the same trade designations, but showing different reference numbers for the same trade patch.

I would interested to know if the lists of reference numbers can be found somewhere, as well as periods during which each list was valid?

I assume that the 3 digits plus letter are the oldest, followed by 5 digits starting with '30' (in this case) and then '33', and finally the most recent being the longer reference starting with 'V086' or 'V087'.