Most of an electronic record is written without anybody deciding to write it. § 395.26(b) lists the eight data elements the device captures automatically: date, time, the vehicle’s geographic location, engine hours, vehicle miles, the driver or authenticated user identification, the vehicle identification, and the motor carrier identification. What matters more than the list is WHEN it fires. The device records those elements at every change of duty status, at log in and log out, when the engine is powered up and powered down, when it detects or clears a malfunction, and — while the vehicle is in motion and nothing else has been recorded in the previous hour — as an intermediate recording on its own initiative. A day therefore has a spine of entries the driver never made, and the driver’s own certification, which the device also records under § 395.26(f), is layered on top of it.

The driver’s input enters at a small number of places, and § 395.28 is where the most consequential of them sits. A motor carrier may configure the device to authorize two special driving categories: authorized personal use, and yard moves. Where a carrier has done so, the driver’s duty under § 395.28(a)(2) is exact in its timing: select the applicable category on the device BEFORE the status starts, deselect it when that status ends, and annotate the record describing the activity when the device prompts for it. Neither category is something a driver switches on by right — the carrier configures the option, and a device that offers neither is a device on which neither is available. A carrier may also configure the device to designate a driver as exempt from its use.

The categories change what gets recorded as well as what it is called, which is the practical reason to select them at the right moment. Under § 395.26(i), a record created while the driver has indicated authorized personal use logs location at a single decimal point resolution — approximately within a 10-mile radius — rather than precisely; and an intermediate recording made during authorized personal use leaves engine hours and vehicle miles blank and logs the coarse location instead. That is the rule quietly distinguishing personal time from working time in the record itself. One further annotation duty catches drivers who think exceptions are silent: under § 395.28(c), a driver operating under an exception in this part, or under one of the subchapter’s exceptions, who is not covered by a special driving category or an exempt designation must annotate the record to explain which exemption applies. § 2.5 sets out the exceptions from the safety regulations; § 8.2 covered the short-haul route.