+Set and lock preferences.
+
+Previously you could only set and lock a subset of preferences. Starting with Firefox 81 and Firefox ESR 78.3 you can set many more preferences. You can also set default preferences, user preferences and you can clear preferences.
+
+Preferences that start with the following prefixes are supported:
+```
+accessibility.
+browser.
+datareporting.policy.
+dom.
+extensions.
+geo.
+intl.
+layout.
+media.
+network.
+places.
+print.
+ui.
+widget.
+```
+as well as the following security preferences:
+```
+security.default_personal_cert
+security.insecure_connection_text.enabled
+security.insecure_connection_text.pbmode.enabled
+security.insecure_field_warning.contextual.enabled
+security.mixed_content.block_active_content
+security.osclientcerts.autoload
+security.ssl.errorReporting.enabled
+security.tls.hello_downgrade_check
+security.warn_submit_secure_to_insecure
+```
+Using the preference as the key, set the `Value` to the corresponding preference value.
+
+`Status` can be "default", "locked", "user" or "clear"
+
+Default preferences can be modified by the user.
+
+If a value is locked, it is also set as the default.
+
+User preferences persist across invocations of Firefox. It is the equivalent of a user setting the preference. They are most useful when a preference is needed very early in startup so it can't be set as a default by policy.
+
+See the examples below for more detail.
+
+IMPORTANT: Make sure you're only setting a particular preference using this mechanism and not some other way.
+
+Status
+**Compatibility:** Firefox 81, Firefox ESR 78.3\
+**CCK2 Equivalent:** `preferences`\
+**Preferences Affected:** Many
+
+#### Windows (GPO)
+```
+Software\Policies\Mozilla\Firefox\Preferences (REG_MULTI_SZ) =
+{
+ "accessibility.force_disabled": {
+ "Value": 1,
+ "Status": "default"
+ },
+ "browser.cache.disk.parent_directory": {
+ "Value": "SOME_NATIVE_PATH",
+ "Status": "user"
+ },
+ "browser.tabs.warnOnClose": {
+ "Value": false,
+ "Status": "locked"
+ }
+}
+```
+#### Windows (Intune)
+OMA-URI:
+```
+./Device/Vendor/MSFT/Policy/Config/Firefox~Policy~firefox/Preferences
+```
+Value (string):
+```
+<enabled/>
+<data id="Preferences" value='
+{
+ "accessibility.force_disabled": {
+ "Value": 1,
+ "Status": "default"
+ },
+ "browser.cache.disk.parent_directory": {
+ "Value": "SOME_NATIVE_PATH",
+ "Status": "user"
+ },
+ "browser.tabs.warnOnClose": {
+ "Value": false,
+ "Status": "locked"
+ }
+}'/>
+```
+#### macOS
+```
+<dict>
+ <key>Preferences</key>
+ <dict>
+ <key>accessibility.force_disabled</key>
+ <dict>
+ <key>Value</key>
+ <integer>1</integer>
+ <key>Status</key>
+ <string>default</string>
+ </dict>
+ <key>browser.cache.disk.parent_directory</key>
+ <dict>
+ <key>Value</key>
+ <string>SOME_NATIVE_PATH</string>
+ <key>Status</key>
+ <string>user</string>
+ </dict>
+ <key>browser.tabs.warnOnClose</key>
+ <dict>
+ <key>Value</key>
+ <false/>
+ <key>Status</key>
+ <string>locked</string>
+ </dict>
+ </dict>
+</dict>
+```
+#### policies.json
+```
+{
+ "policies": {
+ "Preferences": {
+ "accessibility.force_disabled": {
+ "Value": 1,
+ "Status": "default"
+ },
+ "browser.cache.disk.parent_directory": {
+ "Value": "SOME_NATIVE_PATH",
+ "Status": "user"
+ },
+ "browser.tabs.warnOnClose": {
+ "Value": false,
+ "Status": "locked"
+ }
+ }
+ }
+}
+```
+### Preferences (Deprecated)