LinkSubList

Description
A LinkSubList is a data structure that is used as input to various functions and objects; its purpose is to pass a subobject or subelement (vertex, edge, or face) from an object to another object that will use or transform that geometry.

A LinkSubList is composed of a list of tuples.

Each tuple contains at least two elements; the first element is a reference to an object, and the second element is a text string indicating the internal name of the subelement. This name has a number starting with one, and up to the total number of those subelements.

The second element of the tuple can itself be a list of strings, indicating various subelements at the same time.

Scripting
FreeCAD Scripting Basics.

A new scripted object can accept a LinkSubList by adding the corresponding property.

The subelement can then be extracted from the assigned property, and can be manipulated to do something.