New Eras in a tech tree

[Firebug]

If i wanted to add new eras to a tech tree, would it be DLL, Lua or XML?
The reason i ask this is because i want to make a mod which adds extra (maybe a bit quicker) eras.

 

[whoward69]

XML/SQL (database tech updates) and UI context (Lua+XML - tech tree code)

Take care if you repurpose existing eras as the core DLL assumes some key ones (eg industrial) exist and have certain type names (ERA_INDUSTRIAL)