FOG embeds the Glean SDK so its documentation on pings is authoritative. The only detail FOG adds is to clarify the “baseline” ping’s schedule. Specifically, in Firefox Desktop, the application is considered
“active” when started, or when a user interacts with Firefox after a 20min period of inactivity,
“inactive” after the user stops interacting with Firefox after 2min of activity.
For more details about why, see the bug tree around bug 1635242.