Be warned that the evaluation of a shader network for volume rendering is much more expensive than for surface shading, because the shader network is called many times per ray, once per ray march sample. So, in a production environment, it's much better to have a single shader doing all the work, instead of relying on potentially expensive inputs.
When not empty, this channel will be used to sample the scattering values for the volume instead of the Scattering parameter.
A color to tint (multiply to) the scattering.
Henyey-Greenstein Anisotropy coefficient between -1 (full back-scatter) and 1 (full forward-scatter). Default is 0 for an isotropic medium.
Note that values very close to 1.0 (above 0.95) or -1.0 (below -0.95) will produce scattering that is so directional that it will not be very visible from most angles, so such values are not recommended.
A color to tint (multiply to) the attenuation.
Emission is the rate at which a volume emits light at a given point. The light emitted by a volume is visible to GI. It will also be affected by any out-scattering or absorption effects in the volume. A heat (flames) grid would be connected to this parameter.
When not empty, this channel will be used to sample the emission values for the volume instead of the Emission parameter. The sampling tab has additional parameters to control how data is sampled from volume channels.
A color to tint (multiply to) the emission.
The voxel interpolation to use when sampling the volume data using named channels.
An object space offset to apply to the volume sampling position when using named channels to fetch the volume data. This is useful to displace the volume data.
You will need to connect a noise texture to the position offset to see any result.