Auto reporting means that an operation will automatically count down to completion on its own when the operation has started (in process); no reporting of time on the operation is required.  Resources can also be identified as auto reporting on the resource profiles tab. If an operation is scheduled on an auto reporting resource the resource forces the operation to be auto reporting.  If the resource is auto reporting then you may want to set the option to start when previous complete to true as well so that the operation starts automatically when the operation before it has completed.