Item types are the first component of a sequence type, together with the cardinality indicator. Thus, an item type matches (or not) a single item. For example, "foo" matches the item type xs:string.

There are three categories of item types:

JSONiq uses a JSONiq-specific, implementation-defined default type namespace that acts as a proxy namespace to all types (xs: or js:). As a consequence, buitin atomic types do not need to be prefixed in the JSONiq syntax (integer instead of xs:integer, null instead of js:null).

All items match the item type js:item, which is a JSONiq-specific synonym for the W3C-confirmant item().

Figure 5. ItemType