RDF.XSD.Numeric.add

You're seeing just the function add, go back to RDF.XSD.Numeric module for more information.

Adds two numeric literals.

For xsd:float or xsd:double values, if one of the operands is a zero or a finite number and the other is INF or -INF, INF or -INF is returned. If both operands are INF, INF is returned. If both operands are -INF, -INF is returned. If one of the operands is INF and the other is -INF, NaN is returned.

If one of the given arguments is not a numeric literal or a value which can be coerced into a numeric literal, nil is returned.

see http://www.w3.org/TR/xpath-functions/#func-numeric-add