SPARQL Operators are a SPARQL extension that allows you to extend how certain operators in SPARQL are evaluated. You can learn more about operators in the SPARQL Operators page of the Developer Guide.
These may be configured quite simply provided they implement the ISparqlOperator interface and have an unparameterized constructor.
@prefix dnr: <http://www.dotnetrdf.org/configuration#> .
[] a dnr:SparqlOperator ;
dnr:type "VDS.RDF.Query.Operators.DateTime.DateTimeAddition" .