Is the following valid JSON?
A JSON value can be an object, array, number, string, true, false, or null
So basically, ECMA-404 tells us that a JSON value can be either of the above, but only a single one of them. Given your example:
["start", 1234] ["open", 97]
That'd not be considered valid JSON together, at it is not an array, but two arrays, and therefore two JSON values and not one.