Additive toolpaths are created in layers. Material for each physical layer is successively deposited on top of existing layers. You can adjust the thickness of individual layers to address the dynamic attributes of the deposition material such as its thermal properties.
Layer-bands are used to create a common layering index for multiple features. This enables you to group together the toolpath passes of different features, which deposit material in various thickness ranges above the base surface.
When a toolpath is initially calculated each layer is indexed, according to the consecutive passes above the base surface, into layer-bands. In this state the thicknesses and indices of each layer-band correspond to those of the physical layers.
After a toolpath has been calculated you can modify the thicknesses of the layer-bands and re-index them with respect to a common base surface. This results in each layer-band containing various amounts of physical layers.
When you have grouped your toolpath passes into layer-bands, you can split the original toolpaths by layer-band, into new toolpaths. This enables you to arrange the toolpaths so that material is deposited from the passes in each layer-band (for all features), before continuing onto the next layer-band.