docs/DESKTOP_ENVIRONMENT: clarify <RANDOM> usage

The <RANDOM> part is optional in the naming scheme of application units.
However, this is only true for service files. Scope units must include
the <RANDOM> part, otherwise it would be impossible to parse:

The schema would be:

    `app[-<launcher>]-<ApplicationID>[-<RANDOM>].scope`

in which case a two-part name would be impossible to parse, since it is
unclear whether the launcher of the random bit where omitted.

1 files changed, 5 insertions, 5 deletions

diff --git a/docs/DESKTOP_ENVIRONMENTS.md b/docs/DESKTOP_ENVIRONMENTS.md
index ebf4694934..a42efd6791 100644
--- a/docs/DESKTOP_ENVIRONMENTS.md
+++ b/docs/DESKTOP_ENVIRONMENTS.md
@@ -65,11 +65,11 @@ desktop environments should adhere to the following conventions:
    instead of the caller starting the process and letting systemd know about it,
    is encouraged.
 
- * The RANDOM should be a string of random characters to ensure that multiple instances
-   of the application can be launched.
-
-   It can be omitted in the case of a non-transient application services which can ensure
-   multiple instances are not spawned, such as a DBus activated application.
+ * `<RANDOM>` should be a string of random characters to ensure that multiple instances
+   of the application can be launched. This can be omitted for service files of
+   non-transient applications, which ensure multiple instances cannot be
+   spawned. For scope files `<RANDOM>` is mandatory, as the format would be
+   ambiguous otherwise.
 
  * If no application ID is available, the launcher should generate a reasonable
    name when possible (e.g. using `basename(argv[0])`). This name must not