  sdf::Color | Defines a color |
| sdf::Console | Message, error, warning, and logging functionality |
| sdf::ConsolePrivate | |
| sdf::Console::ConsoleStream | An ostream-like class that we'll use for logging |
| sdf::Converter | Convert from one version of SDF to another |
| sdf::ElementPrivate | |
 enable_shared_from_this | |
  sdf::Element | SDF Element class |
| sdf::Exception | Class for generating exceptions |
 sdf::InternalError | Class for generating Internal Gazebo Errors: those errors which should never happend and represent programming bugs |
 sdf::AssertionInternalError | Class for generating Exceptions which come from sdf assertions |
| sdf::ExceptionPrivate | |
| sdf::Inertia | A class for inertial information about a link |
| sdf::Param | A parameter class |
| sdf::ParamPrivate | |
| sdf::Pose | Encapsulates a position and rotation in three space |
| sdf::Quaternion | A quaternion class |
| sdf::SDF | Base SDF class |
| sdf::SDFExtension | |
| sdf::Time | A Time class, can be used to hold wall- or sim-time |
| sdf::URDF2SDF | URDF to SDF converter |
| sdf::Vector2d | Generic double x, y vector |
| sdf::Vector2i | Generic integer x, y vector |
| sdf::Vector3 | Generic vector containing 3 elements. Since it's commonly used to keep coordinate system related information, its elements are labeled by x, y, z |