diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index 9cabc3c4f8..2baf9d17e8 100644
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -189,15 +189,24 @@
suffix is .requires/ in this case.
Along with a unit file foo.service, a "drop-in" directory
- foo.service.d/ may exist. All files with the suffix
- .conf from this directory will be parsed after the file itself is
- parsed. This is useful to alter or add configuration settings for a unit, without having to
- modify unit files. Each drop-in file must have appropriate section headers. Note that for
- instantiated units, this logic will first look for the instance .d/
- subdirectory and read its .conf files, followed by the template
- .d/ subdirectory and the .conf files there.
+ foo.service.d/ may exist. All files with the suffix .conf from this
+ directory will be parsed after the unit file itself is parsed. This is useful to alter or add configuration
+ settings for a unit, without having to modify unit files. Drop-in files must contain appropriate section
+ headers. For instantiated units, this logic will first look for the instance .d/ subdirectory
+ (e.g. foo@bar.service.d/) and read its .conf files, followed by the template
+ .d/ subdirectory (e.g. foo@.service.d/) and the .conf
+ files there. Moreover for units names containing dashes (-), the set of directories generated by
+ truncating the unit name after all dashes is searched too. Specifically, for a unit name
+ foo-bar-baz.service not only the the regular drop-in directory
+ foo-bar-baz.service.d/ is searched but also both foo-bar-.service.d/ and
+ foo-.service.d/. This is useful for defining common drop-ins for a set of related units, whose
+ names begin with a common prefix. This scheme is particularly useful for mount, automount and slice units, whose
+ systematic naming structure is built around dashes as component separators. Note that equally named drop-in files
+ further down the prefix hierarchy override those further up,
+ i.e. foo-bar-.service.d/10-override.conf overrides
+ foo-.service.d/10-override.conf.
- In addition to /etc/systemd/system, the drop-in .d
+ In addition to /etc/systemd/system, the drop-in .d/
directories for system services can be placed in /usr/lib/systemd/system or
/run/systemd/system directories. Drop-in files in /etc
take precedence over those in /run which in turn take precedence over those