For this reason, like to propose а "hybrid" approach; introduce а new standard D-Bus interface, that can be implemented arbitrary applications as a distro sees fit. AccountsService could implement thi

For this reason, like to propose а "hybrid" approach; introduce а
new standard D-Bus interface, that
can be implemented arbitrary applications as a distro sees fit.
AccountsService could implement this API so that newer versions
of distros will get the relevant features for free, while distros with
an AccountsService too old to contain the feature can implement it
themselves as a stop-gap solution.
Taking inspiration from the File Manager D-Bus interface [5], I think
something like the following might work:
<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection
"http://www. freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node
<interface
<method name="SetAge">
<arg type="s" name="User" direction="in"/>
<arg type="u" name="YearsOfAge" direction="in"/>
</method>
<method name="SetDateOfBirth">
<arg type="s" name="User" direction="in"/>
<arg type="s" name="Date" direction="in"/>
</method>
<method name='GetAgeBracket
<arg type="s" name="User" direction="in"/>
<arg type="u" name="AgeBracket" direction="out"/>
</method>
</interface>
</node>