New physics contributions are always defined as contributions to dimension-6 operators in an effective field theory (EFT) below the $W$ mass in the $\overline{\text{MS}}$ renormalization scheme with naive dimensional regularization.

flavio follows the conventions of the Wilson coefficient exchange format (WCxf) that facilitates the exchange of Wilson coefficient values between different codes. New physics contributions in flavio have to be specified in the `flavio`

Wilson coefficient basis for the weak effective theory (WET). The full list of operators can be found in this PDF file: