The Sky shader is considered deprecated and will be removed in a future release. You should instead use the visibility options on the Skydome light instead.
See the Environment page for more information on creating and attaching Sky nodes.
It is recommended to use the Skydome Light for lighting scenes as this uses Multiple Importance Samping (MIS) to fire more rays towards bright, important areas of the environment map. This way, shadow details are preserved, while at the same time keeping noise levels low. There is no need to pre-blur the environment map used for diffuse/glossy rays as you normally would need to do when using the Sky shader. The only situation where using a sky shader may be faster than the Skydome light is when the environment texture is a constant color or has very low variance (see image below). See the Skydome page for reasons why using a Skydome light is more efficient.
Cubic was deprecated in Arnold 184.108.40.206 and removed from HtoA 0.12.
Controls the Sky visibility to specific rays. To ensure the Sky isn't being used as a light, turn off Diffuse and Glossy visibility.
This can be used to link the XYZ axes against an object's orientation. Once picked, the rotation axes of an object is transformed, by a set of expression, into the corresponding axes set. This way, you can simply rotate the object to interactively adjust the sky orientation.