It seems usually you need one type to get another  - workshop - mason - mill for example

Well here https://dl.dropbox.com/u/109779367/market.EleSav

If you take a look at T-Charlie in the SE you'll see a problem.

There is a merchant, and a tax office BUT no market .

THis is a problem since the benenfits are cumulative

Now that I have psotedf this it raises another question in my mind, using the above example I'm pretty sure even if you have both techs you cazn't build mill before the mason

OTOH the merchantcross and Treasury vault are now showing up