Pligg is built upon what framework, if any?

I am trying to modify a Pligg site but the conventions sound too alien too me, So I am wondering which php framework, if any, should I known to start deciphering the Pligg templa开发者_C百科ting language?

Pligg isn't built on any of the known php frameworks.

To be more exact, "Pligg uses a variation of the Smarty template engine, called Template Lite". (reference) However, I am still not sure how much different they are.