According to section 9.13 of RFC7950
The syntax for an instance-identifier is a subset of the XPath abbreviated syntax, formally defined by the rule "instance-identifier" in Section 14. It is used to uniquely identify a node in the data tree. Predicates are used only for specifying the values for the key nodes for list entries, a value of a leaf-list entry, or a positional index for a list without keys. For identifying list entries with keys, each predicate consists of one equality test per key, and each key MUST have a corresponding predicate. If a key is of type "empty", it is represented as a zero-length string ("").
I saw that RFC introduced a word called “positional index”, and it is only “for a list without keys”. Is there any detail information for this?
I want to know how it works, how its value get arranged. Should it start from 0 or 1? negative integer also valid? If changes were done to a certain entry of the list, the index of rest entries will be revalued or not?