Two quick Pontus questions

[Tellos Athenaios]

Most buildings in EB have been designed to allow you 5 different levels; however the engine-side buildings allow for 9. This gives you the ability to overload buildings, say you want to split thech-trees:

Precursor A0 upgrades{A1,A5} bonus lvl 1
Level A1 upgrades {A2} bonus lvl 2
...
Level A3 upgrades {A4} bonus lvl 4
Level A4 bonus lvl 5
Level A5 upgrades {A6} bonus lvl 2
...
Level A7 upgrades {A8} bonus lvl 4
Level A8 bonus lvl 5

However, AFAIK, you cannot 'down-grade'/'upgrade' i.e.:

Level A7 cannot upgrade to Level A4 instead of Level A8. (Hence you cannot build gymnaseia over persian equivalents.)

This thec-tree splitting allows for various things, among others to have a full set of barracks for two reforms on only one building slot; or to stack 9 unique buildings away as one building type; or differentiate between colonies of type a and colonies of type b.