browsingContext.GetTreeParametersExtension = (
  ? "moz:scope": "chrome" / "content",
)

browsingContext.InfoExtension = (
  ? "moz:name": text,
  ? "moz:scope": "chrome" / "content",
)

session.CapabilityRequestExtension = (
  ? "moz:firefoxOptions": session.CapabilityRequestFirefoxOptions,
)

session.CapabilityRequestFirefoxOptions = {
  ? "androidPackage": text,
  ? "androidActivity": text,
  ? "androidDeviceSerial": text,
  ? "androidIntentArguments": [*text],
  ? "args": [*text],
  ? "binary": text,
  ? "env": {*text => text},
  ? "log": {
    ? "level": ("trace" / "debug" / "config" / "info" / "warn" / "error" / "fatal") .default "info"
  },
  ? "prefs": {*text => text / bool / js-int},
  ? "profile": text,
}

webExtension.InstallParametersExtension = (
  ? "moz:allowPrivateBrowsing": bool .default false,
  ? "moz:permanent": bool .default false,
)