O que é o systemd equvalent para sysvinit 'X-Start-Before'?

Question

Citado no link .

X-Start-Before: boot_facility_1 [boot_facility_2...]

X-Stop-After: boot_facility_1 [boot_facility_2...]

provide reverse dependencies, that appear as if the listed facilities had should-start and should-stop on the package with these headers.

Qual é o sistema equvalent para sysvinit X-Start-Before ?

Similar ao Before= do systemd, mas mais strong como dependência.