+.Ss \&%D
+Publication date of an
+.Sx \&Rs
+block. This should follow the reduced or canonical form syntax
+described in
+.Sx Dates .
+.Ss \&%I
+Publisher or issuer name of an
+.Sx \&Rs
+block.
+.Ss \&%J
+Journal name of an
+.Sx \&Rs
+block.
+.Ss \&%N
+Issue number (usually for journals) of an
+.Sx \&Rs
+block.
+.Ss \&%O
+Optional information of an
+.Sx \&Rs
+block.
+.Ss \&%P
+Book or journal page number of an
+.Sx \&Rs
+block.
+.Ss \&%Q
+Institutional author (school, government, etc.) of an
+.Sx \&Rs
+block. Multiple institutional authors should each be accorded their own
+.Sx \&%Q
+line.
+.Ss \&%R
+Technical report name of an
+.Sx \&Rs
+block.
+.Ss \&%T
+Article title of an
+.Sx \&Rs
+block. This macro may also be used in a non-bibliographical context
+when referring to article titles.
+.Ss \&%U
+URI of reference document.
+.Ss \&%V
+Volume number of an
+.Sx \&Rs
+block.
+.Ss \&Ac
+Closes an
+.Sx \&Ao
+block. Does not have any tail arguments.
+.Ss \&Ad
+Address construct: usually in the context of an computational address in
+memory, not a physical (post) address.
+.Pp
+Examples:
+.D1 \&.Ad [0,$]
+.D1 \&.Ad 0x00000000
+.Ss \&An
+Author name.
+This macro may alternatively accepts the following arguments, although
+these may not be specified along with a parameter:
+.Bl -tag -width 12n -offset indent
+.It Fl split
+Renders a line break before each author listing.
+.It Fl nosplit
+The opposite of
+.Fl split .
+.El
+.Pp
+In the AUTHORS section, the default is not to split the first author
+listing, but all subsequent author listings, whether or not they're
+interspersed by other macros or text, are split.
+Thus, specifying
+.Fl split
+will cause the first listing also to be split.
+If not in the AUTHORS section, the default is not to split.
+.Pp
+Examples:
+.D1 \&.An -nosplit
+.D1 \&.An J. D. Ullman .
+.Pp
+.Em Remarks :
+the effects of
+.Fl split
+or
+.Fl nosplit
+are re-set when entering the AUTHORS section, so if one specifies
+.Sx \&An Fl nosplit
+in the general document body, it must be re-specified in the AUTHORS
+section.
+.Ss \&Ao
+Begins a block enclosed by angled brackets.
+Does not have any head arguments.
+.Pp
+Examples:
+.D1 \&.Fl -key= \&Ns \&Ao \&Ar val \&Ac
+.Pp
+See also
+.Sx \&Aq .
+.Ss \&Ap
+Inserts an apostrophe without any surrounding white-space.
+This is generally used as a grammatic device when referring to the verb
+form of a function:
+.Bd -literal -offset indent
+\&.Fn execve Ap d
+.Ed
+.Ss \&Aq
+Encloses its arguments in angled brackets.
+.Pp
+Examples:
+.D1 \&.Fl -key= \&Ns \&Aq \&Ar val
+.Pp
+.Em Remarks :
+this macro is often abused for rendering URIs, which should instead use
+.Sx \&Lk
+or
+.Sx \&Mt ,
+or to note pre-processor
+.Dq Li #include
+statements, which should use
+.Sx \&In .
+.Pp
+See also
+.Sx \&Ao .
+.Ss \&Ar
+Command arguments.
+If an argument is not provided, the string
+.Dq file ...
+is used as a default.
+.Pp
+Examples:
+.D1 \&.Fl o \&Ns \&Ar file1
+.D1 \&.Ar
+.D1 \&.Ar arg1 , arg2 .
+.Ss \&At
+Formats an AT&T version.
+Accepts at most one parameter:
+.Bl -tag -width 12n -offset indent
+.It Cm v[1-7] | 32v
+A version of
+.At .
+.It Cm V[.[1-4]]?
+A system version of
+.At .
+.El
+.Pp
+Note that these parameters do not begin with a hyphen.
+.Pp
+Examples:
+.D1 \&.At
+.D1 \&.At V.1
+.Pp
+See also
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Bc
+Closes a
+.Sx \&Bo
+block. Does not have any tail arguments.
+.Ss \&Bd
+Begins a display block.
+A display is collection of macros or text which may be collectively
+offset or justified in a manner different from that
+of the enclosing context.
+By default, the block is preceded by a vertical space.
+.Pp
+Each display is associated with a type, which must be one of the
+following arguments:
+.Bl -tag -width 12n -offset indent
+.It Fl ragged
+Only left-justify the block.
+.It Fl unfilled
+Do not justify the block at all.
+.It Fl filled
+Left- and right-justify the block.
+.It Fl literal
+Alias for
+.Fl unfilled .
+.It Fl centered
+Centre-justify each line.
+.El
+.Pp
+The type must be provided first.
+Secondary arguments are as follows:
+.Bl -tag -width 12n -offset indent
+.It Fl offset Ar width
+Offset by the value of
+.Ar width ,
+which is interpreted as one of the following, specified in order:
+.Bl -item
+.It
+As one of the pre-defined strings
+.Ar indent ,
+the width of standard indentation;
+.Ar indent-two ,
+twice
+.Ar indent ;
+.Ar left ,
+which has no effect ;
+.Ar right ,
+which justifies to the right margin; and
+.Ar center ,
+which aligns around an imagined centre axis.
+.It
+As a precalculated width for a named macro.
+The most popular is the imaginary macro
+.Ar \&Ds ,
+which resolves to
+.Ar 6n .
+.It
+As a scaling unit following the syntax described in
+.Sx Scaling Widths .
+.It
+As the calculated string length of the opaque string.
+.El
+.Pp
+If unset, it will revert to the value of
+.Ar 8n
+as described in
+.Sx Scaling Widths .
+.It Fl compact
+Do not assert a vertical space before the block.
+.It Fl file Ar file
+Prepend the file
+.Ar file
+before any text or macros within the block.
+.El
+.Pp
+Examples:
+.Bd -literal -offset indent
+\&.Bd \-unfilled \-offset two-indent \-compact
+ Hello world.
+\&.Ed
+.Ed
+.Pp
+See also
+.Sx \&D1
+and
+.Sx \&Dl .
+.Ss \&Bf
+.Ss \&Bk
+.Ss \&Bl
+Begins a list composed of one or more list entries.
+A list is associated with a type, which is a required argument.
+Other arguments are
+.Fl width ,
+defined per-type as accepting a literal or
+.Sx Scaling Widths
+value;
+.Fl offset ,
+also accepting a literal or
+.Sx Scaling Widths
+value setting the list's global offset; and
+.Fl compact ,
+suppressing the default vertical space printed before each list entry.
+A list entry is specified by the
+.Sx \&It
+macro, which consists of a head and optional body (depending on the list
+type).
+A list must specify one of the following list types:
+.Bl -tag -width 12n -offset indent
+.It Fl bullet
+A list offset by a bullet.
+The head of list entries must be empty.
+List entry bodies are positioned after the bullet.
+The
+.Fl width
+argument varies the width of list bodies' left-margins.
+.It Fl column
+A columnated list.
+The
+.Fl width
+argument has no effect.
+The number of columns is specified as parameters to the
+.Sx \&Bl
+macro.
+These dictate the width of columns either as
+.Sx Scaling Widths
+or literal text.
+List entry bodies must be left empty.
+Column bodies have the following syntax:
+.Pp
+.D1 .It col1 <TAB> ... coln
+.D1 .It col1 \&Ta ... coln
+.D1 .It col1 <TAB> col2 \&Ta coln
+.Pp
+where columns may be separated by tabs, the literal string
+.Qq \&Ta ,
+or a mixture of both.
+These are equivalent except that quoted sections propogate over tabs,
+for example,
+.Pp
+.D1 .It \(dqcol1 ; <TAB> col2 ;\(dq ;
+.Pp
+will preserve the semicolon whitespace except for the last.
+.It Fl dash
+A list offset by a dash (hyphen).
+The head of list entries must be empty.
+List entry bodies are positioned past the dash.
+The
+.Fl width
+argument varies the width of list bodies' left-margins.
+.It Fl diag
+Like
+.Fl inset ,
+but with additional formatting to the head.
+The
+.Fl width
+argument varies the width of list bodies' left-margins.
+.It Fl enum
+An enumerated list offset by the enumeration from 1.
+The head of list entries must be empty.
+List entry bodies are positioned after the enumeration.
+The
+.Fl width
+argument varies the width of list bodies' left-margins.
+.It Fl hang
+Like
+.Fl tag ,
+but instead of list bodies positioned after the head, they trail the
+head text.
+The
+.Fl width
+argument varies the width of list bodies' left-margins.
+.It Fl hyphen
+Synonym for
+.Fl dash .
+.It Fl inset
+List bodies follow the list head.
+The
+.Fl width
+argument is ignored.
+.It Fl item
+This produces blocks of text.
+The head of list entries must be empty.
+The
+.Fl width
+argument is ignored.
+.It Fl ohang
+List bodies are positioned on the line following the head.
+The
+.Fl width
+argument is ignored.
+.It Fl tag
+A list offset by list entry heads. List entry bodies are positioned
+after the head as specified by the
+.Fl width
+argument.
+.El
+.Ss \&Bo
+Begins a block enclosed by square brackets.
+Does not have any head arguments.
+.Pp
+Examples:
+.Bd -literal -offset indent
+\&.Bo 1 ,
+\&.Dv BUFSIZ \&Bc
+.Ed
+.Pp
+See also
+.Sx \&Bq .
+.Ss \&Bq
+Encloses its arguments in square brackets.
+.Pp
+Examples:
+.D1 \&.Bq 1 , \&Dv BUFSIZ
+.Pp
+.Em Remarks :
+this macro is sometimes abused to emulate optional arguments for
+commands; the correct macros to use for this purpose are
+.Sx \&Op ,
+.Sx \&Oo ,
+and
+.Sx \&Oc .
+.Pp
+See also
+.Sx \&Bo .
+.Ss \&Brc
+Closes a
+.Sx \&Bro
+block. Does not have any tail arguments.
+.Ss \&Bro
+Begins a block enclosed by curly braces.
+Does not have any head arguments.
+.Pp
+Examples:
+.Bd -literal -offset indent
+\&.Bro 1 , ... ,
+\&.Va n \&Brc
+.Ed
+.Pp
+See also
+.Sx \&Brq .
+.Ss \&Brq
+Encloses its arguments in curly braces.
+.Pp
+Examples:
+.D1 \&.Brq 1 , ... , \&Va n
+.Pp
+See also
+.Sx \&Bro .
+.Ss \&Bsx
+Format the BSD/OS version provided as an argument, or a default value if
+no argument is provided.
+.Pp
+Examples:
+.D1 \&.Bsx 1.0
+.D1 \&.Bsx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Bt
+Prints
+.Dq is currently in beta test.
+.Ss \&Bx
+Format the BSD version provided as an argument, or a default value if no
+argument is provided.
+.Pp
+Examples:
+.D1 \&.Bx 4.4
+.D1 \&.Bx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Cd
+Configuration declaration.
+This denotes strings accepted by
+.Xr config 8 .
+.Pp
+Examples:
+.D1 \&.Cd device le0 at scode?
+.Pp
+.Em Remarks :
+this macro is commonly abused by using quoted literals to retain
+white-space and align consecutive
+.Sx \&Cd
+declarations.
+This practise is discouraged.
+.Ss \&Cm
+Command modifiers.
+Useful when specifying configuration options or keys.
+.Pp
+Examples:
+.D1 \&.Cm ControlPath
+.D1 \&.Cm ControlMaster
+.Pp
+See also
+.Sx \&Fl .
+.Ss \&D1
+One-line indented display.
+This is formatted by the default rules and is useful for simple indented
+statements.
+It is followed by a newline.
+.Pp
+Examples:
+.D1 \&.D1 \&Fl abcdefgh
+.Pp
+See also
+.Sx \&Bd
+and
+.Sx \&Dl .
+.Ss \&Db
+.Ss \&Dc
+Closes a
+.Sx \&Do
+block. Does not have any tail arguments.
+.Ss \&Dd
+Document date.
+This is the mandatory first macro of any
+.Nm
+manual.
+Its calling syntax is as follows:
+.Pp
+.D1 \. Ns Sx \&Dd Cm date
+.Pp
+The
+.Cm date
+field may be either
+.Ar $\&Mdocdate$ ,
+which signifies the current manual revision date dictated by
+.Xr cvs 1 ,
+or instead a valid canonical date as specified by
+.Sx Dates .
+If a date does not conform, the current date is used instead.
+.Pp
+Examples:
+.D1 \&.Dd $\&Mdocdate$
+.D1 \&.Dd $\&Mdocdate: July 21 2007$
+.D1 \&.Dd July 21, 2007
+.Pp
+See also
+.Sx \&Dt
+and
+.Sx \&Os .
+.Ss \&Dl
+One-line intended display.
+This is formatted as literal text and is useful for commands and
+invocations.
+It is followed by a newline.
+.Pp
+Examples:
+.D1 \&.Dl % mandoc mdoc.7 | less
+.Pp
+See also
+.Sx \&Bd
+and
+.Sx \&D1 .
+.Ss \&Do
+Begins a block enclosed by double quotes. Does not have any head
+arguments.
+.Pp
+Examples:
+.D1 \&.D1 \&Do April is the cruellest month \&Dc \e(em T.S. Eliot
+.Pp
+See also
+.Sx \&Dq .
+.Ss \&Dq
+Encloses its arguments in double quotes.
+.Pp
+Examples:
+.Bd -literal -offset indent -compact
+\&.Dq April is the cruellest month
+\e(em T.S. Eliot
+.Ed
+.Pp
+See also
+.Sx \&Do .
+.Ss \&Dt
+Document title.
+This is the mandatory second macro of any
+.Nm
+file.
+Its calling syntax is as follows:
+.Pp
+.D1 \. Ns Sx \&Dt Op Cm title Op Cm section Op Cm volume | arch
+.Pp
+Its arguments are as follows:
+.Bl -tag -width Ds -offset Ds
+.It Cm title
+The document's title (name), defaulting to
+.Qq UNKNOWN
+if unspecified.
+It should be capitalised.
+.It Cm section
+The manual section.
+This may be one of
+.Ar 1
+.Pq utilities ,
+.Ar 2
+.Pq system calls ,
+.Ar 3
+.Pq libraries ,
+.Ar 3p
+.Pq Perl libraries ,
+.Ar 4
+.Pq devices ,
+.Ar 5
+.Pq file formats ,
+.Ar 6
+.Pq games ,
+.Ar 7
+.Pq miscellaneous ,
+.Ar 8
+.Pq system utilities ,
+.Ar 9
+.Pq kernel functions ,
+.Ar X11
+.Pq X Window System ,
+.Ar X11R6
+.Pq X Window System ,
+.Ar unass
+.Pq unassociated ,
+.Ar local
+.Pq local system ,
+.Ar draft
+.Pq draft manual ,
+or
+.Ar paper
+.Pq paper .
+It should correspond to the manual's filename suffix and defaults to
+.Qq 1
+if unspecified.
+.It Cm volume
+This overrides the volume inferred from
+.Ar section .
+This field is optional, and if specified, must be one of
+.Ar USD
+.Pq users' supplementary documents ,
+.Ar PS1
+.Pq programmers' supplementary documents ,
+.Ar AMD
+.Pq administrators' supplementary documents ,
+.Ar SMM
+.Pq system managers' manuals ,
+.Ar URM
+.Pq users' reference manuals ,
+.Ar PRM
+.Pq programmers' reference manuals ,
+.Ar KM
+.Pq kernel manuals ,
+.Ar IND
+.Pq master index ,
+.Ar MMI
+.Pq master index ,
+.Ar LOCAL
+.Pq local manuals ,
+.Ar LOC
+.Pq local manuals ,
+or
+.Ar CON
+.Pq contributed manuals .
+.It Cm arch
+This specifies a specific relevant architecture.
+If
+.Cm volume
+is not provided, it may be used in its place, else it may be used
+subsequent that.
+It, too, is optional.
+It must be one of
+.Ar alpha ,
+.Ar amd64 ,
+.Ar amiga ,
+.Ar arc ,
+.Ar arm ,
+.Ar armish ,
+.Ar aviion ,
+.Ar hp300 ,
+.Ar hppa ,
+.Ar hppa64 ,
+.Ar i386 ,
+.Ar landisk ,
+.Ar loongson ,
+.Ar luna88k ,
+.Ar mac68k ,
+.Ar macppc ,
+.Ar mvme68k ,
+.Ar mvme88k ,
+.Ar mvmeppc ,
+.Ar pmax ,
+.Ar sgi ,
+.Ar socppc ,
+.Ar sparc ,
+.Ar sparc64 ,
+.Ar sun3 ,
+.Ar vax ,
+or
+.Ar zaurus .
+.El
+.Pp
+Examples:
+.D1 \&.Dt FOO 1
+.D1 \&.Dt FOO 4 KM
+.D1 \&.Dt FOO 9 i386
+.Pp
+See also
+.Sx \&Dd
+and
+.Sx \&Os .
+.Ss \&Dv
+Defined variables such as preprocessor constants.
+.Pp
+Examples:
+.D1 \&.Dv BUFSIZ
+.D1 \&.Dv STDOUT_FILENO
+.Pp
+See also
+.Sx \&Er .
+.Ss \&Dx
+Format the DragonFly BSD version provided as an argument, or a default
+value if no argument is provided.
+.Pp
+Examples:
+.D1 \&.Dx 2.4.1
+.D1 \&.Dx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Ec
+.Ss \&Ed
+.Ss \&Ef
+.Ss \&Ek
+.Ss \&El
+.Ss \&Em
+Denotes text that should be emphasised.
+Note that this is a presentation term and should not be used for
+stylistically decorating technical terms.
+.Pp
+Examples:
+.D1 \&.Em Warnings!
+.D1 \&.Em Remarks :
+.Ss \&En
+.Ss \&Eo
+.Ss \&Er
+Display error constants.
+.Pp
+Examples:
+.D1 \&.Er EPERM
+.D1 \&.Er ENOENT
+.Pp
+See also
+.Sx \&Dv .
+.Ss \&Es
+.Ss \&Ev
+Environmental variables such as those specified in
+.Xr environ 7 .
+.Pp
+Examples:
+.D1 \&.Ev DISPLAY
+.D1 \&.Ev PATH
+.Ss \&Ex
+Inserts text regarding a utility's exit values.
+This macro must have first the
+.Fl std
+argument specified, then an optional
+.Ar utility .
+If
+.Ar utility
+is not provided, the document's name as stipulated in
+.Sx \&Nm
+is provided.
+.Ss \&Fa
+.Ss \&Fc
+.Ss \&Fd
+.Ss \&Fl
+Command-line flag.
+Used when listing arguments to command-line utilities.
+Prints a fixed-width hyphen
+.Sq \-
+directly followed by each argument.
+If no arguments are provided, a hyphen is printed followed by a space.
+If the argument is a macro, a hyphen is prefixed to the subsequent macro
+output.
+.Pp
+Examples:
+.D1 \&.Fl a b c
+.D1 \&.Fl \&Pf a b
+.D1 \&.Fl
+.D1 \&.Op \&Fl o \&Ns \&Ar file
+.Pp
+See also
+.Sx \&Cm .
+.Ss \&Fn
+.Ss \&Fo
+.Ss \&Fr
+.Ss \&Ft
+.Ss \&Fx
+Format the FreeBSD version provided as an argument, or a default value
+if no argument is provided.
+.Pp
+Examples:
+.D1 \&.Fx 7.1
+.D1 \&.Fx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Hf
+.Ss \&Ic
+.Ss \&In
+.Ss \&It
+.Ss \&Lb
+Specify a library.
+The calling syntax is as follows:
+.Pp
+.D1 \. Ns Sx \&Lb Cm library
+.Pp
+The
+.Cm library
+parameter may be a system library, such as
+.Cm libz
+or
+.Cm libpam ,
+in which case a small library description is printed next to the linker
+invocation; or a custom library, in which case the library name is
+printed in quotes.
+This is most commonly used in the
+.Em SYNOPSIS
+section as described in
+.Sx MANUAL STRUCTURE .
+.Pp
+Examples:
+.D1 \&.Lb libz
+.D1 \&.Lb mdoc
+.Ss \&Li
+.Ss \&Lk
+Format a hyperlink.
+The calling syntax is as follows:
+.Pp
+.D1 \. Ns Sx \&Lk Cm uri Op Cm name
+.Pp
+Examples:
+.D1 \&.Lk http://bsd.lv "The BSD.lv Project"
+.D1 \&.Lk http://bsd.lv
+.Pp
+See also
+.Sx \&Mt .
+.Ss \&Lp
+.Ss \&Ms
+.Ss \&Mt
+.Ss \&Nd
+.Ss \&Nm
+.Ss \&No
+.Ss \&Ns
+.Ss \&Nx
+Format the NetBSD version provided as an argument, or a default value if
+no argument is provided.
+.Pp
+Examples:
+.D1 \&.Nx 5.01
+.D1 \&.Nx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Oc
+.Ss \&Oo
+.Ss \&Op
+.Ss \&Os
+Document operating system version.
+This is the mandatory third macro of
+any
+.Nm
+file. Its calling syntax is as follows:
+.Pp
+.D1 \. Ns Sx \&Os Op Cm system
+.Pp
+The optional
+.Cm system
+parameter specifies the relevant operating system or environment.
+Left unspecified, it defaults to the local operating system version.
+This is the suggested form.
+.Pp
+Examples:
+.D1 \&.Os
+.D1 \&.Os KTH/CSC/TCS
+.D1 \&.Os BSD 4.3
+.Pp
+See also
+.Sx \&Dd
+and
+.Sx \&Dt .
+.Ss \&Ot
+Unknown usage.
+.Pp
+.Em Remarks :
+this macro has been deprecated.
+.Ss \&Ox
+Format the OpenBSD version provided as an argument, or a default value
+if no argument is provided.
+.Pp
+Examples:
+.D1 \&.Ox 4.5
+.D1 \&.Ox
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+and
+.Sx \&Ux .
+.Ss \&Pa
+.Ss \&Pc
+.Ss \&Pf
+.Ss \&Po
+.Ss \&Pp
+.Ss \&Pq
+.Ss \&Qc
+.Ss \&Ql
+.Ss \&Qo
+.Ss \&Qq
+.Ss \&Re
+Closes a
+.Sx \&Rs
+block.
+Does not have any tail arguments.
+.Ss \&Rs
+Begins a bibliographic
+.Pq Dq reference
+block.
+Does not have any head arguments.
+The block macro may only contain
+.Sx \&%A ,
+.Sx \&%B ,
+.Sx \&%C ,
+.Sx \&%D ,
+.Sx \&%I ,
+.Sx \&%J ,
+.Sx \&%N ,
+.Sx \&%O ,
+.Sx \&%P ,
+.Sx \&%Q ,
+.Sx \&%R ,
+.Sx \&%T ,
+and
+.Sx \&%V
+child macros (at least one must be specified).
+.Pp
+Examples:
+.Bd -literal -offset indent -compact
+\&.Rs
+\&.%A J. E. Hopcroft
+\&.%A J. D. Ullman
+\&.%B Introduction to Automata Theory, Languages, and Computation
+\&.%I Addison-Wesley
+\&.%C Reading, Massachusettes
+\&.%D 1979
+\&.Re
+.Ed
+.Pp
+If an
+.Sx \&Rs
+block is used within a SEE ALSO section, a vertical space is asserted
+before the rendered output, else the block continues on the current
+line.
+.Ss \&Rv
+.Ss \&Sc
+.Ss \&Sh
+.Ss \&Sm
+.Ss \&So
+.Ss \&Sq
+.Ss \&Ss
+.Ss \&St
+.Ss \&Sx
+.Ss \&Sy
+.Ss \&Tn
+.Ss \&Ud
+Prints out
+.Dq currently under development.
+.Ss \&Ux
+Format the UNIX name.
+Accepts no argument.
+.Pp
+Examples:
+.D1 \&.Ux
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+and
+.Sx \&Ox .
+.Ss \&Va
+.Ss \&Vt
+A variable type.
+This is also used for indicating global variables in the SYNOPSIS
+section, in which case a variable name is also specified.
+Note that it accepts
+.Sx Block partial-implicit
+syntax when invoked as the first macro in the SYNOPSIS section, else it
+accepts ordinary
+.Sx In-line
+syntax.
+.Pp
+Note that this should not be confused with
+.Sx \&Ft ,
+which is used for function return types.
+.Pp
+Examples:
+.D1 \&.Vt unsigned char
+.D1 \&.Vt extern const char * const sys_signame[] ;
+.Pp
+See also
+.Sx \&Ft
+and
+.Sx \&Va .
+.Ss \&Xc
+Close a scope opened by
+.Sx \&Xo .
+.Ss \&Xo
+Open an extension scope.
+This macro originally existed to extend the 9-argument limit of troff;
+since this limit has been lifted, the macro has been deprecated.
+.Ss \&Xr
+Link to another manual
+.Pq Qq cross-reference .
+Its calling syntax is
+.Pp
+.D1 \. Ns Sx \&Xr Cm name section
+.Pp
+The
+.Cm name
+and
+.Cm section
+are the name and section of the linked manual.
+If
+.Cm section
+is followed by non-punctuation, an
+.Sx \&Ns
+is inserted into the token stream.
+This behaviour is for compatibility with
+.Xr groff 1 .
+.Pp
+Examples:
+.D1 \&.Xr mandoc 1
+.D1 \&.Xr mandoc 1 ;
+.D1 \&.Xr mandoc 1 \&Ns s behaviour
+.Ss \&br
+.Ss \&sp
+.Sh COMPATIBILITY
+This section documents compatibility between mandoc and other other
+troff implementations, at this time limited to GNU troff
+.Pq Qq groff .