AW: “ALT” is an abbreviation for “Alternative” and refers to a configurable function key, also see device main user manual under “Misc Setup”, where a specific button function can be assigned via the Setup menu. The device features an ALT button field in the HMI. The following direct function assignments for the “ALT” button are available: Camera / FM / Setup / iPod / USB / BT / NAVI / DAB+ / BT source mode / APP List / Mute / Voice / Apple Carplay / Android Auto / BT Music / AV-IN / EQ / DISP / HDMI. Foer more info see device manual under “Various General Settings” p.62-63)