Certain typology rules are written based on the functions present in the OOTB String Groups.
Am not able to understand the existing functions inside the string group say nms:core. Could you please explain with an example for easy understanding?
Most advanced functions are detailed in the JSAPI documentation. Do you have access to this document? It is under licence. See with Support or your CSM for access.
Otherwise, can you specify what you are trying to achieve and what functions you want to discuss?