nonNegativeInteger data type
The xs:nonNegativeInteger data type represents an integer that is greater than or equal to zero. Derived from the xs:integer data type.
The lexical form of xs:nonNegativeInteger is an optional
sign that is followed by a finite-length sequence of decimal digits.
If the sign is omitted, a positive sign (+) is assumed. For lexical
forms that denote zero, the sign can be positive (+) or negative (-).
In all other lexical forms, the sign, if present, must be positive
(+). The range that can be represented by this data type is from 0
to +9223372036854775807. The following numbers are valid examples
of this data type: 1, 0, 12678967543233, and +100000.