Emergency
Intercom menu → Emergency, or Device → Emergency. It sends on the channel you are on. On a DMR channel: a text 'EMERGENCY <message> @ latitude,longitude +-accuracy' to the contact or talkgroup you choose in the sheet (it is remembered). On an analog channel: an APRS position with the emergency symbol and 'EMERGENCY <message>' as the comment, or an EMERGENCY status report when the phone has no position fix; this needs your callsign in PKT → APRS settings.
Hold to send
The red key must be held for two seconds, so a stray tap never sends. Lifting early cancels. Afterwards the sheet says what was sent; hold again to repeat it.
Pick the right channel
Switch to the channel where someone will hear you first: your repeater or talkgroup for DMR, the local APRS frequency (144.390 MHz in North America) for APRS. Only use it for a real emergency.
Roger beep
Device → Roger beep: Off, Beep, Two-tone or Morse K. The tone is sent when you release the talk key, just before the carrier drops, so listeners know you are done. Tapping the row plays the new tone on the phone speaker.