For Galaxy Engine to be able to understand a card, it needs to be expressed as a .cdf file.
Figuring out if CDF stands for "Card Description File" or "Card Definition File" is left as an excercise to the reader.

The structure of a .cdf file is explained in the section 'CDF File Structure'.

Complex effects are written in a bespoke scripting language, called 'CDF Script'.

There are no .cfd Files for tokens as all the info to generate them is contained within the script of the card that creates them.