+.Fl t Sy posixgroup Ns \&, Ns Sy smbgroup .
+.It Xo
+.Nm
+.Cm projectspace
+.Op Fl Hp
+.Oo Fl o Ar field Ns Oo , Ns Ar field Oc Ns ... Oc
+.Oo Fl s Ar field Oc Ns ...
+.Oo Fl S Ar field Oc Ns ...
+.Ar filesystem Ns | Ns Ar snapshot
+.Xc
+Displays space consumed by, and quotas on, each project in the specified
+filesystem or snapshot. This subcommand is identical to
+.Nm zfs Cm userspace ,
+except that the project identifier is numeral, not name. So need neither
+the option
+.Sy -i
+for SID to POSIX ID nor
+.Sy -n
+for numeric ID, nor
+.Sy -t
+for types.
+.It Xo
+.Nm
+.Cm project
+.Oo Fl d Ns | Ns Fl r Ns Oc
+.Ar file Ns | Ns Ar directory Ns ...
+.Xc
+List project identifier (ID) and inherit flag of file(s) or directories.
+.Bl -tag -width "-d"
+.It Fl d
+Show the directory project ID and inherit flag, not its childrens. It will
+overwrite the former specified
+.Fl r
+option.
+.It Fl r
+Show on subdirectories recursively. It will overwrite the former specified
+.Fl d
+option.
+.El
+.It Xo
+.Nm
+.Cm project
+.Fl C
+.Oo Fl kr Ns Oc
+.Ar file Ns | Ns Ar directory Ns ...
+.Xc
+Clear project inherit flag and/or ID on the file(s) or directories.
+.Bl -tag -width "-k"
+.It Fl k
+Keep the project ID unchanged. If not specified, the project ID will be reset
+as zero.
+.It Fl r
+Clear on subdirectories recursively.
+.El
+.It Xo
+.Nm
+.Cm project
+.Fl c
+.Oo Fl 0 Ns Oc
+.Oo Fl d Ns | Ns Fl r Ns Oc
+.Op Fl p Ar id
+.Ar file Ns | Ns Ar directory Ns ...
+.Xc
+Check project ID and inherit flag on the file(s) or directories, report the
+entries without project inherit flag or with different project IDs from the
+specified (via
+.Fl p
+option) value or the target directory's project ID.
+.Bl -tag -width "-0"
+.It Fl 0
+Print file name with a trailing NUL instead of newline (by default), like
+"find -print0".
+.It Fl d
+Check the directory project ID and inherit flag, not its childrens. It will
+overwrite the former specified
+.Fl r
+option.
+.It Fl p
+Specify the referenced ID for comparing with the target file(s) or directories'
+project IDs. If not specified, the target (top) directory's project ID will be
+used as the referenced one.
+.It Fl r
+Check on subdirectories recursively. It will overwrite the former specified
+.Fl d
+option.
+.El
+.It Xo
+.Nm
+.Cm project
+.Op Fl p Ar id
+.Oo Fl rs Ns Oc
+.Ar file Ns | Ns Ar directory Ns ...
+.Xc
+.Bl -tag -width "-p"
+Set project ID and/or inherit flag on the file(s) or directories.
+.It Fl p
+Set the file(s)' or directories' project ID with the given value.
+.It Fl r
+Set on subdirectories recursively.
+.It Fl s
+Set project inherit flag on the given file(s) or directories. It is usually used
+for setup tree quota on the directory target with
+.Fl r
+option specified together. When setup tree quota, by default the directory's
+project ID will be set to all its descendants unless you specify the project
+ID via
+.Fl p
+option explicitly.
+.El