Fixed mhshow part markers when displaying multiple messages.

[nmh] / man / mh-format.man

diff --git a/man/mh-format.man b/man/mh-format.man
index 869aba85d5064c75e7263b86637449a84843bda7..104b8212505a7d906dcafe6cb689f76a4d82974d 100644 (file)
--- a/man/mh-format.man
+++ b/man/mh-format.man
@@ -1,14 +1,9 @@
-.\"
+.TH MH-FORMAT %manext5% 2015-01-10 "%nmhversion%"
+.

 .\" %nmhwarning%
 .\" %nmhwarning%

-.\" $Id$
-.\"
-.TH MH-FORMAT %manext5% "%nmhdate%" MH.6.8 [%nmhversion%]
+.

 .SH NAME
 .SH NAME

-mh-format \- format file for nmh message system
-.SH SYNOPSIS
-some
-.B nmh
-commands
+mh-format \- formatting language for nmh message system

 .SH DESCRIPTION
 Several
 .B nmh
 .SH DESCRIPTION
 Several
 .B nmh


@@ -18,193 +13,207 @@ string or a
 .I format
 file during their execution.  For example,
 .B scan
 .I format
 file during their execution.  For example,
 .B scan

-uses a format string which directs it how to generate the scan listing
-for each message;
+uses a format string to generate its listing of messages;

 .B repl
 .B repl

-uses a format file which directs it
-how to generate the reply to a message, and so on.
-.PP
-Format strings are designed to be efficiently parsed by
-.B nmh
-which means they are not necessarily simple to write and understand.
-This means that novice, casual, or even advanced users of
-.B nmh
-should not have to deal with them.
+uses a format file to generate message replies, and so on.

 .PP
 .PP

-There are a few alternate scan listing formats available
-in
-.IR %etcdir%/scan.time ,
-.IR %etcdir%/scan.size ,
+There are a number of scan listing formats available,
+including
+.IR nmh/etc/scan.time ,
+.IR nmh/etc/scan.size ,

 and
 and

-.IR %etcdir%/scan.timely .
+.IR nmh/etc/scan.timely .

 Look in
 Look in

-.I %etcdir%
+.I %nmhetcdir%

 for other
 .B scan
 and
 .B repl
 format files which may have been written at your site.
 .PP
 for other
 .B scan
 and
 .B repl
 format files which may have been written at your site.
 .PP

-It suffices to have your local
+You can have your local

 .B nmh
 .B nmh

-expert actually write new format
-commands or modify existing ones.  This manual section explains how to
-do that.  Note: familiarity with the C
+expert write new format commands or modify existing ones,
+or you can try your hand at it yourself.
+This manual section explains how to do that.
+Note: some familiarity with the C

 .B printf
 routine is assumed.
 .PP
 .B printf
 routine is assumed.
 .PP

-A format string consists of ordinary text, and special multi-character
-escapesequences which begin with `%'.  When specifying a format
-string, the usual C backslash characters are honored: `\\b', `\\f',
-`\\n', `\\r', and `\\t'.  Continuation lines in format files end with
-`\\' followed by the newline character.
-
+A format string consists of ordinary text combined with special,
+multi-character, escape sequences which begin with `%'.
+When specifying a format string, the usual C backslash characters
+are honored: `\\b', `\\f', `\\n', `\\r', and `\\t'.
+Continuation lines in format files end with `\\' followed by the
+newline character.  A literal `%' can be inserted into a format
+file by using the sequence `%%'.

 .\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
 .SS SYNTAX
 .\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
 .SS SYNTAX

-There are three types of escape sequences: header
+Format strings are built around
+.IR "escape sequences" .
+There are three types of escape sequence: header

 .IR components ,
 built-in
 .IR functions ,
 and flow
 .IR control .
 .IR components ,
 built-in
 .IR functions ,
 and flow
 .IR control .

-.PP
+Comments may be inserted in most places where a function argument is
+not expected.  A comment begins with `%;' and ends with a (non-escaped)
+newline.
+.SS "Component escapes"

 A
 .I component
 escape is specified as
 .RI `%{ component }',
 and
 A
 .I component
 escape is specified as
 .RI `%{ component }',
 and

-exists for each header found in the message being processed.  For example
+exists for each header in the message being processed.  For example,

 .RI `%{ date }'
 .RI `%{ date }'

-refers to the \*(lqDate:\*(rq field of the appropriate message.
-All component escapes have a string value.  Normally, component values are
+refers to the \*(lqDate:\*(rq field of the message.
+All component escapes have a string value.  Such values are usually

 compressed by converting any control characters (tab and newline included)
 compressed by converting any control characters (tab and newline included)

-to spaces, then eliding any leading or multiple spaces.  However, commands
-may give different interpretations to some component escapes; be sure
-to refer to each command's manual entry for complete details.
-.PP
+to spaces, then eliding any leading or multiple spaces.  Some commands,
+however, may interpret some component escapes differently; be sure to
+refer to each command's manual entry for details.
+Some commands (such as
+.IR ap (8)
+and
+.IR mhl (1) )
+use a special component
+.RI `%{ text }'
+to refer to the text being processed; see their respective man pages for
+details and examples.
+.SS "Function escapes"

 A
 .I function
 escape is specified as
 .RI `%( function )'.
 A
 .I function
 escape is specified as
 .RI `%( function )'.

-All functions are built-in, and most have a string or numeric value.
-
-.SS "Control-flow escapes"
+All functions are built-in, and most have a string or integer value.
+A function escape may take an
+.IR argument .
+The argument follows the function escape (and any separating
+whitespace is discarded) as in the following example:
+.PP
+.RS 5
+.nf
+.RI %( function " " argument )
+.fi
+.RE
+.PP
+In addition to literal numbers or strings, the argument to a
+function escape can be another function, or a component,
+or a control escape.  When the argument is a function or a
+component, the argument is specified without a leading `%'.
+When the argument is a control escape, it is specified
+with a leading `%'.
+.SS "Control escapes"

 A
 .I control
 A
 .I control

-escape is one of: `%<', `%?', `%|', or `%>'. 
+escape is one of: `%<', `%?', `%|', or `%>'.

 These are combined into the conditional execution construct:
 .PP
 .RS 5
 .nf
 These are combined into the conditional execution construct:
 .PP
 .RS 5
 .nf

-%<condition
-.RI "  " "format text 1"
-%?condition2
-.RI "  " "format text 2"
-%?condition3
-.RI "  " "format text 3"
-\&...
-%|
-.RI "  " "format text N"
+.RI "%< " condition " " "format-text"
+.RI "%? " condition " " "format-text"
+    ...
+.RI "%| " "format-text"

 %>
 .fi
 .RE
 .PP
 %>
 .fi
 .RE
 .PP

-Extra white space is shown here only for clarity.  These
-constructs may be nested without ambiguity.  They form a general
-.B if\-elseif\-else\-endif
-block where only one of the
-.I format text
-segments is interpreted.
+(Extra white space is shown here only for clarity.)
+These constructs, which may be nested without ambiguity, form a general
+.B if-elseif-else-endif
+block where only one of the format-texts is interpreted.  In other
+words, `%<' is like the "if", `%?' is like the "elseif", `%|' is like
+"else", and `%>' is like "endif".

 .PP
 .PP

-The `%<' and `%?' control escapes causes a condition to be evaluated.  
-This condition may be either a
+A `%<' or `%?' control escape causes its condition to be evaluated.
+This condition is a

 .I component
 .I component

-or a
+or

 .IR function .
 .IR function .

-The four constructs have the following syntax:
-.PP
-.RS 5
-.nf
-%<{component}
-%<(function)
-%?{component}
-%?(function)
-.fi
-.RE
-.PP
-These control escapes test whether the function or component value is
-non-zero (for integer-valued escapes), or non-empty (for string-valued
-escapes).
-.PP
-If this test evaulates true, then the format text up to the next
-corresponding control escape (one of `%|', `%?', or `%>') is interpreted
-normally.  Next, all format text (if any) up to the corresponding `%>'
-control escape is skipped.  The `%>' control escape is not interpreted;
-normal interpretation resumes after the `%>' escape.
-.PP
-If the test evaluates false, however, then the format text up to
-the next corresponding control escape (again, one of `%|', `%?', or
-`%>') is skipped, instead of being interpreted.  If the control escape
-encountered was `%?', then the condition associated with that control
-escape is evaluated, and interpretation proceeds after that test as
-described in the previous paragraph.  If the control escape encountered
-was `%|', then the format text up to the corresponding `%>' escape is
-interpreted normally.  As above, the `%>' escape is not interpreted and
-normal interpretation resumes after the `%>' escape.
-.PP
-The `%?' control escape and its following format text is optional, and may
-be included zero or more times.  The `%|' control escape and its following
-format text is also optional, and may be included zero or one times.
-
+For components and functions whose value is an integer, the condition is true
+if it is non-zero, and false if zero.
+For components and functions whose value is a string, the condition is true
+it is a non-empty string, and false if an empty string.
+.PP
+The `%?' control escape is optional, and can be used multiple times
+in a conditional block.  The `%|' control escape is also optional,
+but may only be used once.

 .SS "Function escapes"
 .SS "Function escapes"

-Most functions expect an argument of a particular type:
+Functions expecting an argument generally require an argument of a
+particular type.  In addition to the integer and string types,
+these include:

 .PP
 .RS 5
 .nf
 .ta +\w'Argument 'u +\w'An optional component, 'u
 .PP
 .RS 5
 .nf
 .ta +\w'Argument 'u +\w'An optional component, 'u

-.I Argument    Description     Example Syntax
-literal        A literal number,       %(\fIfunc\fR 1234)
+.I "Argument   Description     Example Syntax"
+literal        A literal number        %(\fIfunc\fR 1234)

        or string               %(\fIfunc\fR text string)
        or string               %(\fIfunc\fR text string)

-comp   Any header component    %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
+comp   Any component           %(\fIfunc\fR\^{\fIin-reply-to\fR\^})

 date   A date component        %(\fIfunc\fR\^{\fIdate\fR\^})
 addr   An address component    %(\fIfunc\fR\^{\fIfrom\fR\^})
 date   A date component        %(\fIfunc\fR\^{\fIdate\fR\^})
 addr   An address component    %(\fIfunc\fR\^{\fIfrom\fR\^})

-expr   An optional component,  %(\fIfunc\fR\^(\fIfunc2\fR\^))
-       function or control,    %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
-       perhaps nested          %(\fIfunc\fR\^(\fIfunc2\fR\^{\fIcomp\fR\^}))
+expr   Nothing %(\fIfunc\fR)
+       or a subexpression      %(\fIfunc\fR\^(\fIfunc2\fR\^))
+       or control escape       %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-The types
+The

 .I date
 and
 .I addr
 .I date
 and
 .I addr

-have the same syntax as
+types have the same syntax as the component type,

 .IR comp ,
 .IR comp ,

-but require that the header component be a date string, or address
+but require a header component which is a date, or address,

 string, respectively.
 .PP
 string, respectively.
 .PP

-All arguments except those of type
-.IR expr
-are required.  For the
+Most arguments not of type

 .I expr
 .I expr

-argument type, the leading `%' must be omitted for component
-and function escape arguments, and must be present (with a leading space)
-for control escape arguments.
-.PP
-The evaluation of format strings is based on a simple virtual machine
-with an integer register
-.IR num
-, and a text string register
-.IR str .
-When a function escape is processed, if it accepts an optional
+are required.
+When escapes are nested (via expr arguments), evaluation is done
+from innermost to outermost.  As noted above, for the

 .I expr
 .I expr

-argument which is not present, it reads the current value of either
+argument type, functions and components are written without a
+leading `%'.
+Control escape arguments must use a leading `%', preceded by a space.
+.PP
+For example,
+.PP
+.RS 5
+.nf
+%<(mymbox{from}) To: %{to}%>
+.fi
+.RE
+.PP
+writes  the  value of the header component \*(lqFrom:\*(rq to the
+internal register named str; then (\fImymbox\fR\^) reads str and
+writes its result to the internal register named
+.IR num ;
+then the control escape, `%<', evaluates
+.IR num .
+If
+.I num
+is non-zero, the string \*(lqTo:\*(rq is printed followed by the
+value of the header component \*(lqTo:\*(rq.
+.SS Evaluation
+The evaluation of format strings is performed
+by a small virtual machine.
+The machine is capable of evaluating nested expressions
+(as described above) and, in addition, has an integer register
+.IR num ,
+and a text string register
+.IR str .
+When a function escape that accepts an optional argument is processed,
+and the argument is not present, the current value of either

 .I num
 or
 .I str
 .I num
 or
 .I str

-as appropriate.
-
-.SS "Return values"
+is substituted as the argument: the register used depends on the function,
+as listed below.
+.PP

 Component escapes write the value of their message header in
 .IR str .
 Function escapes write their return value in
 Component escapes write the value of their message header in
 .IR str .
 Function escapes write their return value in


@@ -212,36 +221,39 @@ Function escapes write their return value in
 for functions returning integer or boolean values, and in
 .I str
 for functions returning string values.  (The boolean type is a subset
 for functions returning integer or boolean values, and in
 .I str
 for functions returning string values.  (The boolean type is a subset

-of integers with usual values 0=false and 1=true.)  Control escapes
-return a boolean value, and set
-.IR num .
+of integers, with usual values 0=false and 1=true.)  Control escapes
+return a boolean value, setting
+.I num
+to 1 if the last explicit condition
+evaluated by a `%<' or `%?' control escape succeeded, and 0 otherwise.

 .PP
 All component escapes, and those function escapes which return an
 .PP
 All component escapes, and those function escapes which return an

-integer or string value, pass this value back to their caller
-in addition to setting
-I str
+integer or string value, evaluate to their value as well as setting
+.I str

 or
 .IR num .
 or
 .IR num .

-These escapes will print
-out this value unless called as part of an argument to another escape
-sequence.  Escapes which return a boolean value do pass this value
-back to their caller in
-.IR num ,
-but will never print out the value.
+Outermost escape expressions in these forms will print
+their value, but outermost escapes which return a boolean value
+do not result in printed output.
+.SS Functions
+The function escapes may be roughly grouped into a few categories.

 .PP
 .RS 5
 .nf
 .PP
 .RS 5
 .nf

-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function    Argument        Return  Description
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function   Argument        Return  Description"

 msg            integer message number
 msg            integer message number

-cur            integer message is current
-unseen         integer message is unseen
+cur            integer message is current (0 or 1)
+unseen         integer message is unseen (0 or 1)

 size           integer size of message
 strlen         integer length of \fIstr\fR
 size           integer size of message
 strlen         integer length of \fIstr\fR

-width          integer output buffer size in bytes
+width          integer column width of terminal

 charleft               integer bytes left in output buffer
 charleft               integer bytes left in output buffer

-timenow                integer seconds since the UNIX epoch
-me             string  the user's mailbox
+timenow                integer seconds since the Unix epoch
+me             string  the user's mailbox (username)
+myhost         string  the user's local hostname
+myname         string  the user's name
+localmbox              string  the complete local mailbox

 eq     literal boolean \fInum\fR == \fIarg\fR
 ne     literal boolean \fInum\fR != \fIarg\fR
 gt     literal boolean \fInum\fR > \fIarg\fR
 eq     literal boolean \fInum\fR == \fIarg\fR
 ne     literal boolean \fInum\fR != \fIarg\fR
 gt     literal boolean \fInum\fR > \fIarg\fR


@@ -249,12 +261,16 @@ match     literal boolean \fIstr\fR contains \fIarg\fR
 amatch literal boolean \fIstr\fR starts with \fIarg\fR
 plus   literal integer \fIarg\fR plus \fInum\fR
 minus  literal integer \fIarg\fR minus \fInum\fR
 amatch literal boolean \fIstr\fR starts with \fIarg\fR
 plus   literal integer \fIarg\fR plus \fInum\fR
 minus  literal integer \fIarg\fR minus \fInum\fR

+multiply       literal integer \fInum\fR multiplied by \fIarg\fR

 divide literal integer \fInum\fR divided by \fIarg\fR
 modulo literal integer \fInum\fR modulo \fIarg\fR
 divide literal integer \fInum\fR divided by \fIarg\fR
 modulo literal integer \fInum\fR modulo \fIarg\fR

-num    literal integer Set \fInum\fR to \fIarg\fR
-lit    literal string  Set \fIstr\fR to \fIarg\fR
+num    literal integer Set \fInum\fR to \fIarg\fR.
+num            integer Set \fInum\fR to zero.
+lit    literal string  Set \fIstr\fR to \fIarg\fR.
+lit            string  Clear \fIstr\fR.

 getenv         literal string  Set \fIstr\fR to environment value of \fIarg\fR
 getenv         literal string  Set \fIstr\fR to environment value of \fIarg\fR

-profile        literal string  Set \fIstr\fR to profile component \fIarg\fR value
+profile        literal string  Set \fIstr\fR to profile component \fIarg\fR
+                       value

 .\" dat        literal int     return value of dat[arg]
 nonzero        expr    boolean \fInum\fR is non-zero
 zero   expr    boolean \fInum\fR is zero
 .\" dat        literal int     return value of dat[arg]
 nonzero        expr    boolean \fInum\fR is non-zero
 zero   expr    boolean \fInum\fR is zero


@@ -264,23 +280,71 @@ void      expr            Set \fIstr\fR or \fInum\fR
 comp   comp    string  Set \fIstr\fR to component text
 compval        comp    integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
 .\" compflag   comp    integer Set \fInum\fR to component flags bits (internal)
 comp   comp    string  Set \fIstr\fR to component text
 compval        comp    integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
 .\" compflag   comp    integer Set \fInum\fR to component flags bits (internal)

-.\" decodecomp comp    string  Set \fIstr\fR to RFC-2047 decoded component text
-decode expr    string  decode \fIstr\fR as RFC-2047 component
-trim   expr            trim trailing white-space from \fIstr\fR
+.\" decodecomp comp    string  Set \fIstr\fR to RFC 2047 decoded component text
+decode expr    string  decode \fIstr\fR as RFC 2047 (MIME-encoded)
+                       component
+unquote        expr    string  remove RFC 2822 quotes from \fIstr\fR
+trim   expr            trim trailing whitespace from \fIstr\fR
+kilo   expr    string  express in SI units: 15.9K, 2.3M, etc.
+                       %(kilo) scales by factors of 1000,
+kibi   expr    string  express in IEC units: 15.5Ki, 2.2Mi.
+                       %(kibi) scales by factors of 1024.

 putstr expr            print \fIstr\fR
 putstrf        expr            print \fIstr\fR in a fixed width
 putnum expr            print \fInum\fR
 putnumf        expr            print \fInum\fR in a fixed width
 putstr expr            print \fIstr\fR
 putstrf        expr            print \fIstr\fR in a fixed width
 putnum expr            print \fInum\fR
 putnumf        expr            print \fInum\fR in a fixed width

-.\" addtoseq literal    add msg to sequence (LBL option)
+putlit expr            print \fIstr\fR without space compression
+zputlit        expr            print \fIstr\fR without space compression;
+                       \fIstr\fR must occupy no width on display
+bold           string  set terminal bold mode
+underline              string  set terminal underlined mode
+standout               string  set terminal standout mode
+resetterm              string  reset all terminal attributes
+hascolor               boolean terminal supports color
+fgcolor        literal string  set terminal foreground color
+bgcolor        literal string  set terminal background color
+formataddr     expr            append \fIarg\fR to \fIstr\fR as a
+                       (comma separated) address list
+concataddr     expr            append \fIarg\fR to \fIstr\fR as a
+                       (comma separated) address list,
+                       including duplicates,
+                       see Special Handling
+putaddr        literal         print \fIstr\fR address list with
+                       \fIarg\fR as optional label;
+                       get line width from \fInum\fR
+.fi
+.RE
+.PP
+The (\fIme\fR\^) function returns the username of the current user.
+The (\fImyhost\fR\^) function returns the
+.B localname
+entry in
+.IR mts.conf ,
+or the local hostname if
+.B localname
+is not configured.  The (\fImyname\fR\^) function will return the value of
+the
+.B SIGNATURE
+environment variable if set, otherwise it will return the passwd GECOS field
+(truncated at the first comma if it contains one) for
+the current user.  The (\fIlocalmbox\fR\^) function will return the complete
+form of the local mailbox, suitable for use in a \*(lqFrom\*(rq header.
+It will return the
+.RI \*(lq Local-Mailbox \*(rq
+profile entry if there is one; if not, it will be equivalent to:
+.PP
+.RS 5
+.nf
+%(myname) <%(me)@%(myhost)>

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-These functions require a date component as an argument:
+The following functions require a date component as an argument:

 .PP
 .RS 5
 .nf
 .PP
 .RS 5
 .nf

-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function    Argument        Return  Description
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function   Argument        Return  Description"

 sec    date    integer seconds of the minute
 min    date    integer minutes of the hour
 hour   date    integer hours of the day (0-23)
 sec    date    integer seconds of the minute
 min    date    integer minutes of the hour
 hour   date    integer hours of the day (0-23)


@@ -288,92 +352,68 @@ wday      date    integer day of the week (Sun=0)
 day    date    string  day of the week (abbrev.)
 weekday        date    string  day of the week
 sday   date    integer day of the week known?
 day    date    string  day of the week (abbrev.)
 weekday        date    string  day of the week
 sday   date    integer day of the week known?

-                       (0=implicit,\-1=unknown)
+                       (1=explicit,0=implicit,\-1=unknown)

 mday   date    integer day of the month
 yday   date    integer day of the year
 mon    date    integer month of the year
 month  date    string  month of the year (abbrev.)
 lmonth date    string  month of the year
 year   date    integer year (may be > 100)
 mday   date    integer day of the month
 yday   date    integer day of the year
 mon    date    integer month of the year
 month  date    string  month of the year (abbrev.)
 lmonth date    string  month of the year
 year   date    integer year (may be > 100)

-zone   date    integer timezone in hours
+zone   date    integer timezone in minutes

 tzone  date    string  timezone string
 szone  date    integer timezone explicit?
 tzone  date    string  timezone string
 szone  date    integer timezone explicit?

-                       (0=implicit,\-1=unknown)
+                       (1=explicit,0=implicit,\-1=unknown)

 date2local     date            coerce date to local timezone
 date2gmt       date            coerce date to GMT
 date2local     date            coerce date to local timezone
 date2gmt       date            coerce date to GMT

-dst    date    integer daylight savings in effect?
-clock  date    integer seconds since the UNIX epoch
+dst    date    integer daylight savings in effect? (0 or 1)
+clock  date    integer seconds since the Unix epoch

 rclock date    integer seconds prior to current time
 rclock date    integer seconds prior to current time

-tws    date    string  official 822 rendering
+tws    date    string  official RFC 822 rendering

 pretty date    string  user-friendly rendering
 pretty date    string  user-friendly rendering

-nodate date    integer \fIstr\fR not a date string
+nodate date    integer returns 1 if date is invalid

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-These functions require an address component as an argument.  
-The return value of functions noted with `*' pertain only to
+The following functions require an address component as an argument.
+The return value of functions noted with `*' is computed from

 the first address present in the header component.
 .PP
 .RS 5
 .nf
 the first address present in the header component.
 .PP
 .RS 5
 .nf

-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function    Argument        Return  Description
-proper addr    string  official 822 rendering
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function   Argument        Return  Description"
+proper addr    string  official RFC 822 rendering

 friendly       addr    string  user-friendly rendering
 addr   addr    string  mbox@host or host!mbox rendering*
 pers   addr    string  the personal name*
 note   addr    string  commentary text*
 mbox   addr    string  the local mailbox*
 friendly       addr    string  user-friendly rendering
 addr   addr    string  mbox@host or host!mbox rendering*
 pers   addr    string  the personal name*
 note   addr    string  commentary text*
 mbox   addr    string  the local mailbox*

-mymbox addr    integer the user's addresses? (0=no,1=yes)
+mymbox addr    integer list has the user's address? (0 or 1)
+getmymbox      addr    string  the user's (first) address,
+                       with personal name
+getmyaddr      addr    string  the user's (first) address,
+                       without personal name

 host   addr    string  the host domain*
 host   addr    string  the host domain*

-nohost addr    integer no host was present*
+nohost addr    integer no host was present (0 or 1)*

 type   addr    integer host type* (0=local,1=network,
                        \-1=uucp,2=unknown)
 path   addr    string  any leading host route*
 type   addr    integer host type* (0=local,1=network,
                        \-1=uucp,2=unknown)
 path   addr    string  any leading host route*

-ingrp  addr    integer address was inside a group*
+ingrp  addr    integer address was inside a group (0 or 1)*

 gname  addr    string  name of group*
 gname  addr    string  name of group*

-formataddr     expr            append \fIarg\fR to \fIstr\fR as a
-                       (comma separated) address list
-putaddr        literal         print \fIstr\fR address list with
-                       \fIarg\fR as optional label;
-                       get line width from \fInum\fR
-.fi
-.RE
-.PP
-When escapes are nested, evaluation is done from inner-most to outer-most.
-The outer-most escape must begin with `%'; the inner escapes must not.
-For example,
-.PP
-.RS 5
-.nf
-%<(mymbox{from}) To: %{to}%>

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-writes the value of the header component \*(lqFrom:\*(rq to
-.IR str ;
-then (\fImymbox\fR\^) reads
-.I str
-and writes its result to
-.IR num ;
-then the control escape evaluates
-.IR num .
-If
-.I num
-is non-zero, the string \*(lqTo:\*(rq is printed followed by the value of the header
-component \*(lqTo:\*(rq.
-.PP
-A minor explanation of (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
-In general, it checks each of the addresses in the header component
+(A clarification on (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
+This function checks each of the addresses in the header component

 \*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
 .RI \*(lq Alternate-Mailboxes \*(rq.
 \*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
 .RI \*(lq Alternate-Mailboxes \*(rq.

-It returns true if any address matches,
-however, it also returns true if the \*(lq\fIcomp\fR\*(rq header is not
-present in the message.  If needed, the (\fInull\fR\^) function can be
-used to explicitly test for this condition.
-.PP
+It returns true if any address matches. However, it also returns true
+if the \*(lq\fIcomp\fR\*(rq header is not present in the message.
+If needed, the (\fInull\fR\^) function can be used to explicitly
+test for this case.)
+.SS Formatting

 When a function or component escape is interpreted and the result will
 When a function or component escape is interpreted and the result will

-be immediately printed, an optional field width can be specified to
+be printed immediately, an optional field width can be specified to

 print the field in exactly a given number of characters.  For example, a
 numeric escape like %4(\fIsize\fR\^) will print at most 4 digits of the
 message size; overflow will be indicated by a `?' in the first position
 print the field in exactly a given number of characters.  For example, a
 numeric escape like %4(\fIsize\fR\^) will print at most 4 digits of the
 message size; overflow will be indicated by a `?' in the first position


@@ -382,30 +422,142 @@ characters and truncate at the end.  Short fields are padded at the right
 with the fill character (normally, a blank).  If the field width argument
 begins with a leading zero, then the fill character is set to a zero.
 .PP
 with the fill character (normally, a blank).  If the field width argument
 begins with a leading zero, then the fill character is set to a zero.
 .PP

-As above, the functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
+The functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)

 print their result in exactly the number of characters
 specified by their leading field width argument.  For example,
 %06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
 size in a field six characters wide filled with leading zeros;
 %14(\fIputstrf\^\fR{\fIfrom\^\fR}) will print the \*(lqFrom:\*(rq header
 component in fourteen characters with trailing spaces added as needed.
 print their result in exactly the number of characters
 specified by their leading field width argument.  For example,
 %06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
 size in a field six characters wide filled with leading zeros;
 %14(\fIputstrf\^\fR{\fIfrom\^\fR}) will print the \*(lqFrom:\*(rq header
 component in fourteen characters with trailing spaces added as needed.

-For \fIputstrf\fR, using a negative value for the field width causes
-right-justification of the string within the field, with padding on
-the left up to the field width.  The functions (\fIputnum\fR\^) and
-(\fIputstr\fR\^) print their result in the minimum number of characters
-required, and ignore any leading field width argument.
+Using a negative value for the field width causes
+right-justification within the field, with padding on
+the left up to the field width.
+Padding is with spaces except for a left-padded
+.I putnumf
+when the width starts with zero.
+The functions (\fIputnum\fR\^) and
+(\fIputstr\fR\^) are somewhat special: they print their result in the
+minimum number of characters required, and ignore any leading field width
+argument.  The (\fIputlit\fR\^) function outputs the exact contents of the
+str register without any changes such as duplicate space removal or control
+character conversion.  Similarly, the (\fIzputlit\fR\^) function outputs
+the exact contents of the str register, but requires that those contents
+not occupy any output width.  It can therefore be used for outputting
+terminal escape sequences.
+.PP
+There are a limited number of function escapes to output terminal escape
+sequences.  These sequences are retrieved from the
+.IR terminfo (5)
+database according to the current terminal setting.  The (\fIbold\fR\^),
+(\fIunderline\fR\^), and (\fIstandout\fR\^) escapes set bold mode,
+underline mode, and standout mode respectively.
+(\fIhascolor\fR\^)
+can be used to determine if the current terminal supports color.
+(\fIfgcolor\fR\^) and (\fIbgcolor\fR\^) set the foreground and
+background colors respectively.  Both of these escapes take one literal
+argument, the color name, which can be one of: black, red, green, yellow,
+blue, magenta, cyan, white.  (\fIresetterm\fR\^) resets all terminal
+attributes to their default setting.  These terminal escapes should be
+used in conjunction with (\fIzputlit\fR\^) (preferred) or
+(\fIputlit\fR\^), as the normal (\fIputstr\fR\^) function will strip
+out control characters.

 .PP
 The available output width is kept in an internal register; any output
 .PP
 The available output width is kept in an internal register; any output

-past this width will be truncated.
+exceeding this width will be truncated.  The one exception to this is that
+(\fIzputlit\fR\^) functions will still be executed if a terminal
+reset code is being placed at the end of a line.
+.SS Special Handling
+Some functions have different behavior depending on the command they are
+invoked from.
+.PP
+In
+.B repl
+the (\fIformataddr\fR\^) function stores all email addresses encountered into
+an internal cache and will use this cache to suppress duplicate addresses.
+If you need to create an address list that includes previously-seen
+addresses you may use the (\fIconcataddr\fR\^) function, which is identical
+to (\fIformataddr\fR\^) in all other respects.  Note that (\fIconcataddr\fR\^)
+does
+.I not
+add addresses to the duplicate-suppression cache.
+.SS Other Hints and Tips
+Sometimes, the writer of a format function is confused because output is
+duplicated.  The general rule to remember is simple: If a function or
+component escape begins with a `%', it will generate text in the output file.
+Otherwise, it will not.
+.PP
+A good example is a simple attempt to generate a To: header based on
+the From: and Reply-To: headers:

 .PP
 .PP

-Comments may be inserted in most places where a function argument is
-not expected.  A comment begins with `%;' and ends with a (non-escaped)
-newline.
+.RS 5
+.nf
+%(formataddr %<{reply-to}%|%{from})%(putaddr To: )
+.fi
+.RE

 .PP
 .PP

-With all this in mind,
-here's the default format string for
+Unfortunately, if the Reply-to: header is
+.I not
+present, the output line
+will be something like:
+.PP
+.RS 5
+.nf
+My From User <from@example.com>To: My From User <from@example.com>
+.fi
+.RE
+.PP
+What went wrong?  When performing the test for the
+.B if
+clause (%<), the component is not output because it is considered an
+argument to the
+.B if
+statement (so the rule about not starting with % applies).  But the component
+escape in our
+.B else
+statement (everything after the `%|') is
+.I not
+an argument to anything;
+it begins with a %, and thus the value of that component is output.
+This also has the side effect of setting the
+.I str
+register, which is later picked up by the (\fIformataddr\fR\^) function
+and then output by (\fIputaddr\fR\^).  The example format string above
+has another bug: there should always be a valid width value in the
+.I num
+register when (\fIputaddr\fR\^) is called, otherwise bad formatting can take
+place.
+.PP
+The solution is to use the (\fIvoid\fR\^) function; this will prevent the
+function or component from outputting any text.  With this in place (and
+using (\fIwidth\fR\^) to set the
+.I num
+register for the width) a better implementation would look like:
+.PP
+.RS 3
+.nf
+%(formataddr %<{reply-to}%|%(void{from})%(void(width))%(putaddr To: )
+.fi
+.RE
+.PP
+It should be noted here that the side effects of function and component
+escapes are still in force and, as a result, each component test in the
+.B if-elseif-else-endif
+clause sets the
+.I str
+register.
+.PP
+As an additional note, the (\fIformataddr\fR\^) and (\fIconcataddr\fR\^)
+functions have special behavior when it comes to the
+.I str
+register.  The starting point of the register is saved and is used to
+build up entries in the address list.
+.PP
+You will find the
+.IR fmttest (1)
+utility invaluable when debugging problems with format strings.
+.SS Examples
+With all the above in mind, here is a breakdown of the default format string for

 .BR scan .
 .BR scan .

-It's been divided into several pieces for readability.

 The first part is:
 .PP
 .RS
 The first part is:
 .PP
 .RS


@@ -414,11 +566,11 @@ The first part is:
 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-which says that the message number should be printed in four digits,
-if the message is the current message then a `+' else a space should
-be printed, and if a \*(lqReplied:\*(rq field is present then a `\-'
-else if an \*(lqEncrypted:\*(rq field is present then an `E' otherwise
-a space should be printed.  Next:
+which says that the message number should be printed in four digits.
+If the message is the current message then a `+', else a space, should
+be printed; if a \*(lqReplied:\*(rq field is present then a `\-',
+else if an \*(lqEncrypted:\*(rq field is present then an `E', otherwise
+a space, should be printed.  Next:

 .PP
 .RS
 .nf
 .PP
 .RS
 .nf


@@ -427,51 +579,50 @@ a space should be printed.  Next:
 .RE
 .PP
 the month and date are printed in two digits (zero filled) separated by
 .RE
 .PP
 the month and date are printed in two digits (zero filled) separated by

-a slash. Next,
+a slash.  Next,

 .PP
 .RS 5
 .nf
 .PP
 .RS 5
 .nf

-%<{date} %|*>
+%<{date} %|*%>

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-If a \*(lqDate:\*(rq field was present,
-then a space is printed, otherwise a `*'.
+If a \*(lqDate:\*(rq field is present it is printed, followed by a space;
+otherwise a `*' is printed.

 Next,
 .PP
 .RS 5
 .nf
 Next,
 .PP
 .RS 5
 .nf

-%<(mymbox{from})%<{to}To:%14(friendly{to})%>%>
+%<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-if the message is from me,
-and there is a \*(lqTo:\*(rq header,
-print `To:' followed by a \*(lquser-friendly\*(rq rendering of the 
-first address in the \*(lqTo:\*(rq field.
+if the message is from me, and there is a \*(lqTo:\*(rq header,
+print \*(lqTo:\*(rq followed by a \*(lquser-friendly\*(rq rendering of the
+first address in the \*(lqTo:\*(rq field; any MIME-encoded
+characters are decoded into the actual characters.

 Continuing,
 .PP
 .RS 5
 .nf
 Continuing,
 .PP
 .RS 5
 .nf

-%<(zero)%17(friendly{from})%>
+%<(zero)%17(decode(friendly{from}))%>

 .fi
 .RE
 .PP
 if either of the above two tests failed,
 then the \*(lqFrom:\*(rq address is printed
 .fi
 .RE
 .PP
 if either of the above two tests failed,
 then the \*(lqFrom:\*(rq address is printed

-in a \*(lquser-friendly\*(rq format.
+in a mime-decoded, \*(lquser-friendly\*(rq format.

 And finally,
 .PP
 .RS 5
 .nf
 And finally,
 .PP
 .RS 5
 .nf

-%{subject}%<{body}<<%{body}%>
+%(decode{subject})%<{body}<<%{body}>>%>

 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-the subject and initial body (if any) are printed.
+the mime-decoded subject and initial body (if any) are printed.

 .PP
 .PP

-For a more complicated example, next consider
-the default
+For a more complicated example, consider a possible

 .I replcomps
 format file.
 .PP
 .I replcomps
 format file.
 .PP


@@ -483,7 +634,7 @@ format file.
 .PP
 This clears
 .I str
 .PP
 This clears
 .I str

-and formats the \*(lqReply-To:\*(rq header 
+and formats the \*(lqReply-To:\*(rq header

 if present.  If not present, the else-if clause is executed.
 .PP
 .RS 5
 if present.  If not present, the else-if clause is executed.
 .PP
 .RS 5


@@ -492,7 +643,7 @@ if present.  If not present, the else-if clause is executed.
 .fi
 .RE
 .PP
 .fi
 .RE
 .PP

-This formats the 
+This formats the

 \*(lqFrom:\*(rq, \*(lqSender:\*(rq and \*(lqReturn-Path:\*(rq
 headers, stopping as soon as one of them is present.  Next:
 .PP
 \*(lqFrom:\*(rq, \*(lqSender:\*(rq and \*(lqReturn-Path:\*(rq
 headers, stopping as soon as one of them is present.  Next:
 .PP


@@ -504,7 +655,7 @@ headers, stopping as soon as one of them is present.  Next:
 .PP
 If the \fIformataddr\fR result is non-null, it is printed as
 an address (with line folding if needed) in a field \fIwidth\fR
 .PP
 If the \fIformataddr\fR result is non-null, it is printed as
 an address (with line folding if needed) in a field \fIwidth\fR

-wide with a leading label of \*(lqTo:\*(rq.
+wide, with a leading label of \*(lqTo:\*(rq.

 .PP
 .RS 5
 .nf
 .PP
 .RS 5
 .nf


@@ -538,7 +689,7 @@ If a
 switch was given to
 .B repl
 (see
 switch was given to
 .B repl
 (see

-.BR repl (1)
+.IR repl (1)

 for more details about %{\fIfcc\fR\^}),
 an \*(lqFcc:\*(rq header is output.
 .PP
 for more details about %{\fIfcc\fR\^}),
 an \*(lqFcc:\*(rq header is output.
 .PP


@@ -553,17 +704,17 @@ a suitable reply subject is output.
 .PP
 .RS 5
 .nf
 .PP
 .RS 5
 .nf

-%<{date}In-reply-to: Your message of "\\
-%<(nodate{date})%{date}%|%(pretty{date})%>."%<{message-id}
-             %{message-id}%>\\n%>\\
+%<{message-id}In-Reply-To: %{message-id}\\n%>\\
+%<{message-id}References: %<{references} %{references}%>\\
+%{message-id}\\n%>

 \-\-\-\-\-\-\-\-
 .fi
 .RE
 .PP
 \-\-\-\-\-\-\-\-
 .fi
 .RE
 .PP

-If a date component was present, an \*(lqIn-Reply-To:\*(rq header is
-output with the preface \*(lqYour message of \*(rq.  If the date was
-parseable, it is output in a user-friendly format, otherwise it is
-output as-is.  The message-id is included if present.  As with all
+If a message-id component was present, an \*(lqIn-Reply-To:\*(rq header is
+output including the message-id, followed by a \*(lqReferences:\*(rq
+header with references, if present, and the message-id.
+As with all

 plain-text, the row of dashes are output as-is.
 .PP
 This last part is a good example for a little more elaboration.
 plain-text, the row of dashes are output as-is.
 .PP
 This last part is a good example for a little more elaboration.


@@ -572,30 +723,61 @@ Here's that part again in pseudo-code:
 .RS 5
 .nf
 .ta .5i 1i 1.5i 2i
 .RS 5
 .nf
 .ta .5i 1i 1.5i 2i

-if (comp_exists(date))  then
-       print (\*(lqIn-reply-to: Your message of \\\*(lq\*(rq)
-       if (not_date_string(date.value) then
-               print (date.value)
-       else
-               print (pretty(date.value))
-       endif
-       print (\*(lq\\\*(rq\*(rq)
-       if (comp_exists(message-id)) then
-               print (\*(lq\\n\\t\*(rq)
-               print (message-id.value)
+if (comp_exists(message-id))  then
+       print (\*(lqIn-reply-to: \*(rq)
+       print (message-id.value)
+       print (\*(lq\\n\*(rq)
+endif
+if (comp_exists(message-id)) then
+       print (\*(lqReferences: \*(rq)
+       if (comp_exists(references)) then
+             print(references.value);

        endif
        endif

+       print (message-id.value)

        print (\*(lq\\n\*(rq)
 endif
 .fi
 .RE
 .PP
        print (\*(lq\\n\*(rq)
 endif
 .fi
 .RE
 .PP

-Although this seems complicated,
-in point of fact,
-this method is flexible enough to extract individual fields and print them in
-any format the user desires.
-
+.\" (Note that this pseudocode begs the question ``why not just
+.\" support this syntax?''  MH has been hacked on for a long time...)
+.\".PP
+One more example: Currently,
+.B nmh
+supports very large message numbers, and it is not uncommon for a folder
+to have far more than 10000 messages.
+.\" (Indeed, the original MH
+.\" tutorial document by Rose and Romine is entitled "How to
+.\" process 200 messages a day and still get some real work
+.\" done."  The authors apparently only planned to get
+.\" real work done for about 50 days per folder.)
+Nonetheless (as noted above) the various scan format strings, inherited
+from older MH versions, are generally hard-coded to 4 digits for the message
+number. Thereafter, formatting problems occur.
+The nmh format strings can be modified to behave more sensibly with larger
+message numbers:
+.PP
+.RS
+.nf
+%(void(msg))%<(gt 9999)%(msg)%|%4(msg)%>
+.fi
+.RE
+.PP
+The current message number is placed in \fInum\fP.
+(Note that
+.RI ( msg )
+is a function escape which returns an integer, it is not a component.)
+The
+.RI ( gt )
+conditional
+is used to test whether the message number
+has 5
+or more digits.
+If so, it is printed at full width, otherwise
+at 4 digits.

 .SH "SEE ALSO"
 .SH "SEE ALSO"

-scan(1), repl(1), ap(8), dp(8)
-
+.IR scan (1),
+.IR repl (1),
+.IR fmttest (1)

 .SH CONTEXT
 None
 .SH CONTEXT
 None