Represents which BatchRendererGroup batch layers to enable for rendering.
Unity renders the object if you enable the BatchFilterSettings.batchLayer value in this bit mask. You can use BatchFilterSettings.batchLayer to specify a batch layer in each BatchDrawRange.
Objects that are not rendered using BatchRendererGroup are in batch layer 0, so you can use bit 0 of batchLayerMask to control whether they're included in this renderer list.