The finite elements used by Advance Design engine are based on “2 – node edge element (linear)” shape function.
Advance Design uses also “3 – node edge element (quadratic)” shape function but, currently, it is disabled. It will be available in a future version.
Unfortunately, we don’t have any manual from where you can find more detailed information about this subject, but I have attached a picture with a short description of shape functions aforementioned for linear elements.
Attachment: shape functions.zip