Systemd equivalent of single-user mode

Hi,

Under SysVinit, one could type

init 1

to go into single-user (aka maintenance) mode. What is the equivalent of this command under systemd?

Thanks in advance.

PS: This question came up while going through Section 2.6.a Main directory layout of the course. In that section, the Purpose of /bin is described as Essential executable programs that must be available in single-user mode.