Identify the missing word(s) in the following sentence within the context of Microsoft Azure. A(n) [?] document is enclosed in curly brackets ({ and }). Each field has a name (a label), followed by a colon, and then the value of the field. Fields can contain simple values, or sub-documents (each starting and ending with curly brackets). Fields can also have multiple values, held as arrays and surrounded with square brackets ([ and ]). Literals in a field are enclosed in quotes, and fields are separated with commas.