"A subscript used to access an element or subrange in a [[ElementOrSubrangeExpression]] (where it is surrounded by brackets). In mathematical notations, these accessors are usually written as subscript, e. g. *x<sub>i</sub>* for the *i*<sup>th</sup> *x* element. Examples: index ... text.size - 2" shared abstract class Subscript() of KeySubscript | RangeSubscript extends Node() { }