Product Numbering & Bar Code Verification of Phantom Plarail Sets

A new problem arises as we found out that Basic No. 3 Set is G-26 (1977), and the box design is the yellow EC box. This breaks this generalisation of the G-nn to MS-nn numbering system:

2. We also know that the earliest MS series is MS-28 which is the Blue Train Set (1979), some sets of the Mid Hikari-Go Mark Era (yellow box sets (also known as 5th Gen EC Box)) are manufactured in 1977 (like the Basic Set No. 3). This tells us the the alphabets in the number series change according to box design, not by production era. (Summarised version of the conversation)

We were expecting it to be MS-26, however it is not the case.

The confirmed number progression is G-20, G-21 ... G-27, MS-28, MS-29...
Once I get my Basic No. 3 Set with the Panorama Limited Express, I will reconfirm my number with the L Limited Express version.
It looks like the research still has to continue...