You can perform calculation on any multi-field, multi-band raster similar to any single-field, single-band raster. By default, each field of a multi-field grid will be processed in sequence, using the same expression. However, individual fields can also be specified similarly to bands.
To refer to an individual field, you should select the required field from the input dropdown. You can select any field and the alias will refer to the selected field from the raster.
To perform an operation on any specific band from the selected field, insert the field alias in the expression and open square brackets to get a list of all the bands from the selected field. Select the required band form the list. For example, Input_1[0] refers to Band00.