There are several options that can be set on serializers, called features. The exact list of features can be found via Querying Functionality or in the API reference for raptor_serializer_set_feature().

Features are integer enumerations of the raptor_feature enum and have values that are either integers (often acting as booleans) or strings. The two functions that set features are:

  /* Set an integer (or boolean) valued feature */
  raptor_serializer_set_feature(rdf_serializer, feature, 1);

  /* Set a string valued feature */
  raptor_serializer_set_feature_string(rdf_serializer, feature, "abc");

There are also two corresponding functions for reading the values of serializer features: raptor_serializer_get_feature() and raptor_serializer_get_feature_string() taken the feature enumeration parameter and returning the integer or string value correspondingly.