Using reserved word field name in DocumentDB
You are correct. Value is a reserved keyword. To escape this use [""] syntax.
So in your case of
"Alternates": [ "Type": "ID", "Value" : "NOCALL" ]
SELECT c FROM cJOIN alt IN c.AlternatesWHERE alt["Value"] = 'NOCALL'
In my case, the structure looks something like this - { "name": "ABC", "Value": 123 }.
I could escape the reserved keyword using [""] (as answered by others) along with <source_name> i.e.
SELECT c["Value"] FROM c -- 123