+.Pp
+Using anything other than
+.Sq m ,
+.Sq n ,
+.Sq u ,
+or
+.Sq v
+is necessarily non-portable across output media. See
+.Sx COMPATIBILITY .
+.
+.
+.Sh MANUAL STRUCTURE
+A well-formed
+.Nm
+document consists of a document prologue followed by one or more
+sections.
+.Pp
+The prologue, which consists of (in order) the
+.Sx \&Dd ,
+.Sx \&Dt ,
+and
+.Sx \&Os
+macros, is required for every document.
+.Pp
+The first section (sections are denoted by
+.Sx \&Sh )
+must be the NAME section, consisting of at least one
+.Sx \&Nm
+followed by
+.Sx \&Nd .
+.Pp
+Following that, convention dictates specifying at least the SYNOPSIS and
+DESCRIPTION sections, although this varies between manual sections.
+.Pp
+The following is a well-formed skeleton
+.Nm
+file:
+.Bd -literal -offset indent
+\&.Dd $\&Mdocdate$
+\&.Dt mdoc 7
+\&.Os
+\&.
+\&.Sh NAME
+\&.Nm foo
+\&.Nd a description goes here
+\&.\e\*q The next is for sections 2 & 3 only.
+\&.\e\*q .Sh LIBRARY
+\&.
+\&.Sh SYNOPSIS
+\&.Nm foo
+\&.Op Fl options
+\&.Ar
+\&.
+\&.Sh DESCRIPTION
+The
+\&.Nm
+utility processes files ...
+\&.\e\*q .Sh IMPLEMENTATION NOTES
+\&.\e\*q The next is for sections 1 & 8 only.
+\&.\e\*q .Sh EXIT STATUS
+\&.\e\*q The next is for sections 2, 3, & 9 only.
+\&.\e\*q .Sh RETURN VALUES
+\&.\e\*q The next is for sections 1, 6, 7, & 8 only.
+\&.\e\*q .Sh ENVIRONMENT
+\&.\e\*q .Sh FILES
+\&.\e\*q .Sh EXAMPLES
+\&.\e\*q The next is for sections 1, 4, 6, 7, & 8 only.
+\&.\e\*q .Sh DIAGNOSTICS
+\&.\e\*q The next is for sections 2, 3, & 9 only.
+\&.\e\*q .Sh ERRORS
+\&.\e\*q .Sh SEE ALSO
+\&.\e\*q .Xr foobar 1
+\&.\e\*q .Sh STANDARDS
+\&.\e\*q .Sh HISTORY
+\&.\e\*q .Sh AUTHORS
+\&.\e\*q .Sh CAVEATS
+\&.\e\*q .Sh BUGS
+\&.\e\*q .Sh SECURITY CONSIDERATIONS
+.Ed
+.Pp
+The sections in a
+.Nm
+document are conventionally ordered as they appear above. Sections
+should be composed as follows:
+.Bl -ohang -offset Ds
+.It Em NAME
+The name(s) and a short description of the documented material. The
+syntax for this as follows:
+.Bd -literal -offset indent
+\&.Nm name0
+\&.Nm name1
+\&.Nm name2
+\&.Nd a short description
+.Ed
+.Pp
+The
+.Sx \&Nm
+macro(s) must precede the
+.Sx \&Nd
+macro.
+.Pp
+See
+.Sx \&Nm
+and
+.Sx \&Nd .
+.
+.It Em LIBRARY
+The name of the library containing the documented material, which is
+assumed to be a function in a section 2 or 3 manual. The syntax for
+this is as follows:
+.Bd -literal -offset indent
+\&.Lb libarm
+.Ed
+.Pp
+See
+.Sx \&Lb .
+.
+.It Em SYNOPSIS
+Documents the utility invocation syntax, function call syntax, or device
+configuration.
+.Pp
+For the first, utilities (sections 1, 6, and 8), this is
+generally structured as follows:
+.Bd -literal -offset indent
+\&.Nm foo
+\&.Op Fl v
+\&.Op Fl o Ar file
+\&.Op Ar
+\&.Nm bar
+\&.Op Fl v
+\&.Op Fl o Ar file
+\&.Op Ar
+.Ed
+.Pp
+For the second, function calls (sections 2, 3, 9):
+.Bd -literal -offset indent
+\&.Vt extern const char *global;
+\&.In header.h
+\&.Ft "char *"
+\&.Fn foo "const char *src"
+\&.Ft "char *"
+\&.Fn bar "const char *src"
+.Ed
+.Pp
+And for the third, configurations (section 4):
+.Bd -literal -offset indent
+\&.Cd \*qit* at isa? port 0x2e\*q
+\&.Cd \*qit* at isa? port 0x4e\*q
+.Ed
+.Pp
+Manuals not in these sections generally don't need a
+.Em SYNOPSIS .
+.Pp
+See
+.Sx \&Op ,
+.Sx \&Cd ,
+.Sx \&Fn ,
+.Sx \&Ft ,
+and
+.Sx \&Vt .
+.
+.It Em DESCRIPTION
+This expands upon the brief, one-line description in
+.Em NAME .
+It usually contains a break-down of the options (if documenting a
+command), such as:
+.Bd -literal -offset indent
+The arguments are as follows:
+\&.Bl \-tag \-width Ds
+\&.It Fl v
+Print verbose information.
+\&.El
+.Ed
+.Pp
+Manuals not documenting a command won't include the above fragment.
+.
+.It Em IMPLEMENTATION NOTES
+Implementation-specific notes should be kept here. This is useful when
+implementing standard functions that may have side effects or notable
+algorithmic implications.
+.
+.It Em EXIT STATUS
+Command exit status for section 1, 6, and 8 manuals. This section is
+the dual of
+.Em RETURN VALUES ,
+which is used for functions. Historically, this information was
+described in
+.Em DIAGNOSTICS ,
+a practise that is now discouraged.
+.Pp
+See
+.Sx \&Ex .
+.
+.It Em RETURN VALUES
+This section is the dual of
+.Em EXIT STATUS ,
+which is used for commands. It documents the return values of functions
+in sections 2, 3, and 9.
+.Pp
+See
+.Sx \&Rv .
+.
+.It Em ENVIRONMENT
+Documents any usages of environment variables, e.g.,
+.Xr environ 7 .
+.Pp
+See
+.Sx \&Ev .
+.
+.It Em FILES
+Documents files used. It's helpful to document both the file and a
+short description of how the file is used (created, modified, etc.).
+.Pp
+See
+.Sx \&Pa .
+.
+.It Em EXAMPLES
+Example usages. This often contains snippets of well-formed,
+well-tested invocations. Make doubly sure that your examples work
+properly!
+.
+.It Em DIAGNOSTICS
+Documents error conditions. This is most useful in section 4 manuals.
+Historically, this section was used in place of
+.Em EXIT STATUS
+for manuals in sections 1, 6, and 8; however, this practise is
+discouraged.
+.Pp
+See
+.Sx \&Bl
+.Fl diag .
+.
+.It Em ERRORS
+Documents error handling in sections 2, 3, and 9.
+.Pp
+See
+.Sx \&Er .
+.
+.It Em SEE ALSO
+References other manuals with related topics. This section should exist
+for most manuals. Cross-references should conventionally be ordered
+first by section, then alphabetically.
+.Pp
+See
+.Sx \&Xr .
+.
+.It Em STANDARDS
+References any standards implemented or used. If not adhering to any
+standards, the
+.Em HISTORY
+section should be used instead.
+.Pp
+See
+.Sx \&St .
+.
+.It Em HISTORY
+The history of any manual without a
+.Em STANDARDS
+section should be described in this section.
+.
+.It Em AUTHORS
+Credits to authors, if applicable, should appear in this section.
+Authors should generally be noted by both name and an e-mail address.
+.Pp
+See
+.Sx \&An .
+.
+.It Em CAVEATS
+Explanations of common misuses and misunderstandings should be explained
+in this section.
+.
+.It Em BUGS
+Extant bugs should be described in this section.
+.
+.It Em SECURITY CONSIDERATIONS
+Documents any security precautions that operators should consider.
+.