diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml
index 075caffb2bf..cdab87ab63e 100644
--- a/man/sd_id128_get_machine.xml
+++ b/man/sd_id128_get_machine.xml
@@ -94,10 +94,20 @@
has properties similar to the machine ID during that time.
sd_id128_get_invocation() returns the invocation ID of the currently executed
- service. In its current implementation, this reads and parses the $INVOCATION_ID environment
- variable that the service manager sets when activating a service, see
- systemd.exec5 for details. The
- ID is cached internally. In future a different mechanism to determine the invocation ID may be added.
+ service. In its current implementation, this tries to read and parse the following:
+
+
+ The $INVOCATION_ID environment variable that the service manager sets when
+ activating a service.
+
+
+ An entry in the kernel keyring that the system service manager sets when activating a service.
+
+
+
+ See systemd.exec5
+ for details. The ID is cached internally. In future a different mechanism to determine the invocation ID
+ may be added.
Note that sd_id128_get_machine_app_specific(),
sd_id128_get_boot(), sd_id128_get_boot_app_specific(), and