The world element encapsulates an entire world description including: models, scene, physics, 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. Included resources can only contain one 'model', 'light' or 'actor' element. The URI can point to a directory or a file. If the URI is a directory, it must conform to the model database structure (see /tutorials?tut=composition&cat=specification&#defining-models-in-separate-files). Merge the included model into the top model. Only elements valid in 'world' are allowed in the included model URI to a resource, such as a model Override the name of the included entity. Override the static value of the included entity. The frame inside the included entity whose pose will be set by the specified pose element. If this element is specified, the pose must be specified. 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.