The world element encapsulates an entire world description including: models, scene, physics, joints, and plugins Unique name of the world Global audio properties. Device to use for audio playback. A value of "default" will use the system's default audio device. Otherwise, specify a an audio device file" The wind tag specifies the type and properties of the wind. Linear velocity of the wind. Include resources from a URI URI to a resource, such as a model Override the name of the included model. Override the static value of the included model. The gravity vector in m/s^2, expressed in a coordinate frame defined by the spherical_coordinates tag. The magnetic vector in Tesla, expressed in a coordinate frame defined by the spherical_coordinates tag.