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+.TH ACME 1
+.SH NAME
+acme, win \- interactive text windows
+.SH SYNOPSIS
+.B acme
+[
+.B -f
+.I varfont
+]
+[
+.B -F
+.I fixfont
+]
+[
+.B -c
+.I ncol
+]
+[
+.B -b
+]
+[
+.B -l
+.I file
+|
+.I file
+\&... ]
+.LP
+.B win
+[
+.I command
+]
+.SH DESCRIPTION
+.I Acme
+manages windows of text that may be edited interactively or by external programs.
+The interactive interface uses the keyboard and mouse; external programs
+use a set of files served by
+.IR acme ;
+these are discussed in
+.IR acme (4).
+.PP
+Any named
+.I files
+are read into
+.I acme
+windows before
+.I acme
+accepts input.
+With the
+.B -l
+option, the state of the entire system is loaded
+from
+.IR file ,
+which should have been created by a
+.B Dump
+command (q.v.),
+and subsequent
+.I file
+names are ignored.
+Plain files display as text; directories display as columnated lists of the
+names of their components with the names of subdirectories having a slash appended.
+.PP
+The
+.B -f
+.RB ( -F )
+option sets the default variable-pitch (fixed-pitch)
+font; the default is
+.B /fonts/lucidasans/euro.8.font
+.RB ( \&.../lucm/unicode.9.font ).
+Tab intervals are set to the width of 4 numeral zeros in the variable-pitch font.
+.PP
+.SS Windows
+.I Acme
+windows are in two parts: a one-line
+.I tag
+above a multi-line
+.IR body .
+The body typically contains an image of a file or the output of a program.
+The tag contains a number of
+blank-separated words, followed by a vertical bar character, followed by anything.
+The first word is the name of the window, typically the name of the associated
+file or directory, and the other words are commands available in that window.
+Any text may be added after the bar; examples are strings to search for or
+commands to execute in that window.
+Changes to the text left of the bar will be ignored,
+unless the result is to change the name of the
+window.
+.PP
+If a window holds a directory, the name (first word of the tag) will end with
+a slash.
+.SS Scrolling
+Each window has a scroll bar to the left of the body.
+Scrolling occurs when the button is pressed, rather than released,
+and continues
+as long as the mouse button is held down in the scroll bar.
+For example, to scroll slowly through a file,
+hold button 3 down near the top of the scroll bar.  Moving the mouse
+down the scroll bar speeds up the rate of scrolling. Scrolling backwards is performed
+similarly using button 1. Button 2 allows absolute movement within the text; clicking it
+at different heights within the scroll bar changes the focused text without intermediate
+scrolling.
+.SS Layout
+.I Acme
+windows are arranged in columns.  By default, it creates two columns when starting;
+this can be overridden with the
+.B -c
+option.
+Placement is automatic but may be adjusted
+using the
+.I layout box
+in the upper left corner of each window and column.
+Pressing and holding any mouse button in the box drags
+the associated window or column.
+For windows, just
+clicking in the layout box grows the window in place: button 1
+grows it a little, button 2 grows it as much as it can, still leaving all other
+tags in that column visible, and button 3 takes over the column completely,
+temporarily hiding other windows in the column.
+(They will return
+.I en masse
+if any of them needs attention.)
+The layout box in a window is normally white; when it is black in the center,
+it records that the file is `dirty':
+.I Acme
+believes it is modified from its original
+contents.
+.PP
+Tags exist at the top of each column and across the whole display.
+.I Acme
+pre-loads them with useful commands.
+Also, the tag across the top maintains a list of executing long-running commands.
+.SS Typing
+The behaviour of typed text is as one would expect
+except that the characters are delivered to the tag or body under the mouse; there is no
+`click to type'.
+(The experimental option
+.B -b
+causes typing to go to the most recently clicked-at or made window.)
+The usual backspacing conventions apply.
+The ESC key selects the text typed since the last mouse action,
+a feature particularly useful when executing commands.
+A side effect is that typing ESC with text already selected is identical
+to a
+.B Cut
+command
+.RI ( q.v. ).
+.PP
+Most text, including the names of windows, may be edited uniformly.
+The only exception is that the command names to the
+left of the bar in a tag are maintained automatically; changes to them are repaired
+by
+.IR acme .
+.SS "Directory context
+Each window's tag names a directory: explicitly if the window
+holds a directory; implicitly if it holds a regular file
+(e.g. the directory
+.B /module
+if the window holds
+.BR /module/sys.m ).
+This directory provides a
+.I context
+for interpreting file names in that window.
+For example, the string
+.B sys.m
+in a window labelled
+.B /module/
+or
+.B /module/draw.m
+will be interpreted as the file name
+.BR /module/sys.m .
+The directory is defined purely textually, so it can be a non-existent
+directory or a real directory associated with a non-existent file
+(e.g.
+.BR /module/not-a-file ).
+File names beginning with a slash
+are assumed to be absolute file names.
+.SS Errors
+Windows whose names begin with
+.B -
+or
+.B +
+conventionally hold diagnostics and other data
+not directly associated with files.
+A window labelled
+.B +Errors
+receives all diagnostics produced by
+.I acme
+itself.
+Diagnostics from commands run by
+.I acme
+appear in a window named
+.IB directory /+Errors
+where
+.I directory
+is identified by the context of the command.
+These error windows are created when needed.
+.SS "Mouse button 1
+Mouse button 1 selects text and double-clicking highlights the text for replacement text to be
+typed in. 
+.PP
+Button 1 is also useful for matching symbols. For example to match curly brackets in some limbo
+source, 
+double click button 1 immediately after the open curly bracket.
+The whole of the text up to any matching end curly bracket will be highlighted. A similar match
+is made if the double click is performed immediately before the end bracket. In all,
+.I acme
+will match the pairs { and }, [ and ], ( and ), < and >, « and », ' and ', " and ", ` and `.
+Also whole lines of text may be highlighted by double clicking at the beginning or end of the line.
+.SS "Mouse button 2
+By an
+action similar to selecting text with button 1,
+button 2 indicates text to execute as a command.
+If the indicated text has multiple white-space-separated words,
+the first is the command name and the second and subsequent
+are its arguments.
+If button 2 is `clicked'\(emindicates a null string\(em\c
+.I acme
+.I expands
+the indicated text to find a command to run:
+if the click is within button-1-selected text,
+.I acme
+takes that selection as the command;
+otherwise it takes the largest string of valid file name characters containing the click.
+Valid file name characters are alphanumerics and
+.B _
+.B .
+.B -
+.B +
+.BR / .
+This behaviour is similar to double-clicking with button 1 but,
+because a null command is meaningless, only a single click is required.
+.PP
+Some commands, all by convention starting with a capital letter, are
+.I built-ins
+that are executed directly by
+.IR acme :
+.TF "Lineno\ \ "
+.PD
+.TP
+.B Cut
+Delete most recently selected text and place in snarf buffer.
+.TP
+.B Del
+Delete window.  If window is dirty, instead print a warning; a second
+.B Del
+will succeed.
+.TP
+.B Delcol
+Delete column and all its windows, after checking that windows are not dirty.
+.TP
+.B Delete
+Delete window without checking for dirtiness.
+.TP
+.B Dump
+Write the state of
+.I acme
+to the file name, if specified, or
+.B $home/acme.dump
+by default.
+.TP
+.B Edit
+Treat the argument as a text editing command in the style of Plan9's
+.IR sam.
+The full
+.B Sam
+language is implemented except for the commands
+.BR k ,
+.BR n ,
+.BR q ,
+and
+.BR ! .
+The
+.B =
+command is slightly different: it includes the file name and
+gives only the line address unless the command is explicitly
+.BR =# .
+The `current window' for the command is the body of the window in which the
+.B Edit
+command is executed.
+Usually the
+.B Edit
+command would be typed in a tag; longer commands may be prepared in a
+scratch window and executed, with
+.B Edit
+itself in the current window, using the 2-1 chord described below. See the later
+section on editing for a full description of the commands available here.
+.TP
+.B Exit
+Exit
+.I acme
+after checking that windows are not dirty.
+.TP
+.B Font
+With no arguments, change the font of the associated window from fixed-spaced to
+proportional-spaced or
+.I vice versa\f1.
+Given a file name argument, change the font of the window to that stored in the named file.
+If the file name argument is prefixed by
+.B var
+.RB ( fix ),
+also set the default proportional-spaced (fixed-spaced) font for future use to that font.
+Other existing windows are unaffected.
+.TP
+.B Get
+Load file into window, replacing previous contents (after checking for dirtiness as in
+.BR Del ).
+With no argument, use the existing file name of the window.
+Given an argument, use that file but do not change the window's file name.
+.TP
+.B ID
+Print window ID number
+.RI ( q.v. ).
+.TP
+.B Incl
+When opening `include' files with button 3,
+.I acme
+searches in the directories
+.B /module
+and
+.B /include .
+.B Incl
+adds its arguments to a supplementary list of include directories, analogous to
+the
+.B -I
+option to the compilers.
+This list is per-window and is inherited when windows are created by actions in that window, so
+.I Incl
+is most usefully applied to a directory containing relevant source.
+With no arguments,
+.I Incl
+prints the supplementary list.
+.TP
+.B Kill
+Send a
+.B kill
+note to
+.IR acme -initiated
+commands named as arguments.
+.TP
+.B Lineno
+Give the line number(s) of the currently selected text.
+.TP
+.B Load
+Restore the state of
+.I acme
+from a file (default
+.BR $home/acme.dump )
+created by the
+.B Dump
+command.
+.TP
+.B Local
+When prefixed to a command
+run the
+command in the same file name space and environment variable group as
+.IR acme .
+The environment of the command
+is restricted but is sufficient to run
+.IR bind (1),
+.IR mount ,
+etc.,
+and to set environment variables.
+.TP
+.B Look
+Search in body for occurrence of literal text indicated by the argument or,
+if none is given, by the selected text in the body.
+.TP
+.B New
+Make new window.  With arguments, load the named files into windows.
+.TP
+.B Newcol
+Make new column.
+.TP
+.B Paste
+Replace most recently selected text with contents of snarf buffer.
+.TP
+.B Put
+Write window to the named file.
+With no argument, write to the file named in the tag of the window.
+.TP
+.B Putall
+Write all dirty windows whose names indicate existing regular files.
+.TP
+.B Redo
+Complement of
+.BR Undo .
+.TP
+.B Send
+Append selected text or snarf buffer to end of body; used mainly with
+.IR win .
+.TP
+.B Snarf
+Place selected text in snarf buffer.
+.TP
+.B Sort
+Arrange the windows in the column from top to bottom in lexicographical
+order based on their names.
+.TP
+.B Undo
+Undo last textual change or set of changes.
+.TP
+.B Zerox
+Create a copy of the window containing most recently selected text.
+.PP
+A common place to store text for commands is in the tag; in fact
+.I acme
+maintains a set of commands appropriate to the state of the window
+to the left of the bar in the tag.
+.PP
+If the text indicated with button 2 is not a recognized built-in, it is executed as
+a shell command.  For example, indicating
+.B date
+with button 2 runs
+.IR date (1).
+The standard
+and error outputs of commands are sent to the error window associated with
+the directory from which the command was run, which will be created if
+necessary.
+For example, in a window
+.B /module/sys.m
+executing
+.B pwd
+will produce the output
+.B /module
+in a (possibly newly-created) window labelled
+.BR /adm/+Errors ;
+in a window containing
+.B /appl/cmd/date.b
+executing
+.B "limbo date.b"
+will run
+.IR limbo (1)
+in
+.BR /appl/cmd ,
+producing output in a window labelled
+.BR /appl/cmd/+Errors .
+.SS "Mouse button 3
+Pointing at text with button 3 instructs
+.I acme
+to locate or acquire the file, string, etc. described by the indicated text and
+its context.
+This description follows the actions taken when
+button 3 is released after sweeping out some text.
+In the description,
+.I text
+refers to the text of the original sweep or, if it was null, the result of
+applying the same expansion rules that apply to button 2 actions.
+.PP
+If the text names an existing window,
+.I acme
+moves the mouse cursor to the selected text in the body of that window.
+If the text names an existing file with no associated window,
+.I acme
+loads the file into a new window and moves the mouse there.
+If the text is a file name contained in double quotes,
+.I acme
+loads the indicated include file from the directory appropriate to the
+suffix of the file name of the window holding the text.
+(The
+.B Incl
+command adds directories to the standard list.)
+.PP
+If the text begins with a colon, it is taken to be an address
+within the body of the window containing the text.
+The address is evaluated, the resulting text highlighted, and the mouse moved to it.
+Thus, in
+.IR acme ,
+one must type
+.B :/regexp
+or
+.B :127
+not just
+.B /regexp
+or
+.BR 127 .
+(There is an easier way to locate literal text; see below.)
+.PP
+If the text is a file name followed by a colon and an address,
+.I acme
+loads the file and evaluates the address.  For example, clicking button 3 anywhere
+in the text
+.B file.c:27
+will open
+.BR file.c ,
+select line
+27, and put the mouse at the beginning of the line.  The rules about Error
+files, directories, and so on all combine to make this an efficient way to
+investigate errors from compilers, etc.
+.PP
+If the text is not an address or file, it is taken to
+be literal text, which is then searched for in the body of the window
+in which button 3 was clicked.  If a match is found, it is selected and the mouse is
+moved there.  Thus, to search for occurrences of a word in a file,
+just click button 3 on the word.  Because of the rule of using the
+selection as the button 3 action, subsequent clicks will find subsequent
+occurrences without moving the mouse.
+.PP
+In all these actions, the mouse motion is not done if the text is a null string
+within a non-null selected string in the tag, so that (for example) complex regular expressions
+may be selected and applied repeatedly to the
+body by just clicking button 3 over them.
+.SS "Chords of mouse buttons
+Several operations are bound to multiple-button actions.
+After selecting text, with button 1 still down, pressing button 2
+executes
+.B Cut
+and button 3 executes
+.BR Paste .
+After clicking one button, the other undoes
+the first; thus (while holding down button 1) 2 followed by 3 is a
+.B Snarf
+that leaves the file undirtied;
+3 followed by 2 is a no-op.
+These actions also apply to text selected by double-clicking because
+the double-click expansion is made when the second
+click starts, not when it ends.
+.PP
+Thus to copy a word a number of times, double click on the word with button 1 to highlight it leaving
+button 1 down, press and release button 2 to cut it and save it in the snarf buffer, press and 
+release button 3 to paste it back and then release button 1. Now move the cursor to any selected
+place in the text, press button 1 down, then button 3 and the word is copied in.
+.PP
+Similarly lines may be deleted by double clicking at the beginning or end of the line and then 
+pressing button 2 with button 1 still down.
+.PP
+Commands may be given extra arguments by a mouse chord with buttons 2 and 1.
+While holding down button 2 on text to be executed as a command, clicking button 1
+appends the text last pointed to by button 1 as a distinct final argument.
+For example, to search for literal
+.B text
+one may execute
+.B Look text
+with button 2 or instead point at
+.B text
+with button 1 in any window, release button 1,
+then execute
+.BR Look ,
+clicking button 1 while 2 is held down.
+.PP
+When an external command (e.g.
+.IR echo (1))
+is executed this way, the extra argument is passed as expected and an
+environment variable
+.B $acmeaddr
+is created that holds, in the form interpreted by button 3,
+the fully-qualified address of the extra argument.
+.SS "Support programs
+.I win
+creates a new
+.I acme
+window and runs a
+.I command
+(default
+.BR /dis/sh.dis )
+in it, turning the window into a shell window in which commands may be executed.
+Executing text in a
+.I win
+window with button
+2 is similar to using
+.BR Send .
+.PP
+Similarly
+.I winm
+creates a new window but runs the shell
+.BR /dis/mash.dis
+by default.
+.I adiff
+behaves as diff in finding the difference between two files but the listing uses
+filename:linenumber format to allow the user to simply click on this to be sent to that line
+in the file.
+.I agrep
+does for grep what adiff does for diff above.
+.I cd
+changes directory but when used in a win window for example, sends information to the
+window to display a new heading reflecting the new directory.
+.SS "Mail"
+In the directory 
+.B /acme/mail
+there are two mail programs that may be used under acme. These
+.I Mail
+and
+.I Mailpop3
+can be run to display the user's current mail, read the mail, reply to mail, save or delete mail,
+send mail and write the user's mail box.
+.PP
+The former expects the user's mail box to be in the directory and file specified as its first argument,
+the latter uses the POP3 protocol to connect to a server for the user's mail and will prompt for a 
+password when first run. Otherwise their behaviour is the same.
+.SS "Applications and guide files
+In the directory
+.B /acme
+live several subdirectories, each corresponding to a program or
+set of related programs that employ
+.I acme's
+user interface.
+Each subdirectory includes dis files and a
+.B readme
+file for further information.
+It also includes a
+.BR guide ,
+a text file holding sample commands to invoke the programs.
+The idea is to find an example in the guide that best matches
+the job at hand, edit it to suit, and execute it.
+.PP
+Whenever a command is executed by
+.IR acme ,
+the default search path includes the directory of the window containing
+the command.
+Also,
+.I acme
+binds the directory
+.B /acme/dis
+in front of
+.B /dis
+when it starts; this is where
+.IR acme -specific
+programs such as
+.I win
+reside.
+.SH EDITING
+This section explains the commands available when using acme's Edit command.
+.PP
+.SS Regular expressions
+Regular expressions are as in
+.IR regexp (6)
+with the addition of
+.BR \en
+to represent newlines.
+A regular expression may never contain a literal newline character.
+The empty
+regular expression stands for the last complete expression encountered.
+A regular expression
+matches the longest leftmost substring formally
+matched by the expression.
+Searching in the reverse direction is equivalent
+to searching backwards with the catenation operations reversed in
+the expression.
+.SS Addresses
+An address identifies a substring in a file.
+In the following, `character
+.IR n '
+means the null string
+after the
+.IR n -th
+character in the file, with 1 the
+first character in the file.
+`Line
+.IR n '
+means the
+.IR n -th
+match,
+starting at the beginning of the file, of the regular expression
+.LR .*\en? .
+All files always have a current substring, called dot,
+that is the default address.
+.SS Simple Addresses
+.PD0
+.TP
+.BI # n
+The empty string after character
+.IR n ;
+.B #0
+is the beginning of the file.
+.TP
+.I n
+Line
+.IR n ;
+.B 0
+is the beginning of the file.
+.TP
+.BI  / regexp /
+.PD0
+.TP
+.BI ? regexp ?
+The substring that matches the regular expression,
+found by looking toward the end 
+.RB ( / )
+or beginning
+.RB ( ? )
+of the file,
+and if necessary continuing the search from the other end to the
+starting point of the search.
+The matched substring may straddle
+the starting point.
+When entering a pattern containing a literal question mark
+for a backward search, the question mark should be
+specified as a member of a class.
+.PD
+.TP
+.B 0
+The string before the first full line.
+This is not necessarily
+the null string; see
+.B +
+and
+.B -
+below.
+.TP
+.B $
+The null string at the end of the file.
+.TP
+.B .
+Dot.
+.TP
+.B \&'
+The mark in the file.
+.TP
+\fL"regexp"\fP
+Preceding a simple address (default
+.BR . ),
+refers to the address evaluated in the unique file whose menu line
+matches the regular expression.
+.PD
+.SS Compound Addresses
+In the following,
+.I a1
+and
+.I a2
+are addresses.
+.TF a1+a2
+.TP
+.IB a1 + a2
+The address
+.I a2
+evaluated starting at the end of
+.IR a1 .
+.TP
+.IB a1 - a2
+The address
+.I a2
+evaluated looking in the reverse direction
+starting at the beginning of
+.IR a1 .
+.TP
+.IB a1 , a2
+The substring from the beginning of
+.I a1
+to the end of
+.IR a2 .
+If
+.I a1
+is missing,
+.B 0
+is substituted.
+If
+.I a2
+is missing,
+.B $
+is substituted.
+.TP
+.IB  a1 ; a2
+Like
+.IB a1 , a2\f1,
+but with
+.I a2
+evaluated at the end of, and dot set to,
+.IR a1 .
+.PD
+.PP
+The operators
+.B +
+and
+.B -
+are high precedence, while
+.B ,
+and
+.B ;
+are low precedence.
+.PP
+In both
+.B +
+and
+.B -
+forms, if
+.I a2
+is a line or character address with a missing
+number, the number defaults to 1.
+If
+.I a1
+is missing,
+.L .
+is substituted.
+If both
+.I a1
+and
+.I a2
+are present and distinguishable,
+.B +
+may be elided.
+.I a2
+may be a regular
+expression; if it is delimited by
+.LR ? 's,
+the effect of the
+.B +
+or
+.B -
+is reversed.
+.PP
+It is an error for a compound address to represent a malformed substring.
+Some useful idioms: 
+.IB a1 +-
+(\f2a1-+\fP)
+selects the line containing
+the end (beginning) of a1.
+.BI 0/ regexp /
+locates the first match of the expression in the file.
+(The form
+.B 0;//
+sets dot unnecessarily.)
+.BI ./ regexp /// 
+finds the second following occurrence of the expression,
+and
+.BI .,/ regexp /
+extends dot.
+.SS Commands
+In the following, text demarcated by slashes represents text delimited
+by any printable
+character except alphanumerics.
+Any number of
+trailing delimiters may be elided, with multiple elisions then representing
+null strings, but the first delimiter must always
+be present.
+In any delimited text,
+newline may not appear literally;
+.B \en
+may be typed for newline; and
+.B \e/
+quotes the delimiter, here 
+.LR / .
+Backslash is otherwise interpreted literally, except in
+.B s
+commands.
+.PP
+Most commands may be prefixed by an address to indicate their range
+of operation.
+Those that may not are marked with a 
+.L *
+below.
+If a command takes
+an address and none is supplied, dot is used.
+The sole exception is
+the
+.B w
+command, which defaults to
+.BR 0,$ .
+In the description, `range' is used
+to represent whatever address is supplied.
+Many commands set the
+value of dot as a side effect.
+If so, it is always set to the `result'
+of the change: the empty string for a deletion, the new text for an
+insertion, etc. (but see the
+.B s
+and
+.B e
+commands).
+.br
+.ne 1.2i
+.SS Text commands
+.PD0
+.TP
+.BI a/ text /
+.TP
+or
+.TP
+.B  a
+.TP
+.I lines of text
+.TP
+.B .
+Insert the text into the file after the range.
+Set dot.
+.PD
+.TP
+.B c\fP
+.br
+.ns
+.TP
+.B i\fP
+Same as
+.BR a ,
+but
+.B c
+replaces the text, while
+.B i
+inserts
+.I before
+the range.
+.TP
+.B d
+Delete the text in the range.
+Set dot.
+.TP
+.BI s/ regexp / text /
+Substitute
+.I text
+for the first match to the regular expression in the range.
+Set dot to the modified range.
+In 
+.I text
+the character
+.B &
+stands for the string
+that matched the expression. 
+Backslash behaves as usual unless followed by
+a digit:
+.BI \e d
+stands for the string that matched the
+subexpression begun by the
+.IR d -th
+left parenthesis.
+If
+.I s
+is followed immediately by a
+number
+.IR n ,
+as in
+.BR s2/x/y/ ,
+the
+.IR n -th
+match in the range is substituted.
+If the
+command is followed by a
+.BR g ,
+as in
+.BR s/x/y/g ,
+all matches in the range
+are substituted.
+.TP
+.BI m " a1
+.br
+.ns
+.TP
+.BI t " a1
+Move
+.RB ( m )
+or copy
+.RB ( t )
+the range to after
+.IR a1 .
+Set dot.
+.SS Display commands
+.PD 0
+.TP
+.B p
+Print the text in the range.
+Set dot.
+.TP
+.B =
+Print the file name and line address of the range.
+.TP
+.B =#
+Print the file name and character address of the range.
+.PD
+.SS File commands
+.PD0
+.TP
+.BI * " b " file-list
+Set the current file to the first file named in the list
+that
+.I acme
+has displayed.
+The list may be expressed
+.BI < "command"
+in which case the file names are taken as words (in the shell sense)
+generated by the command.
+.TP
+.BI * " B " file-list
+Same as
+.BR b ,
+except that file names not displayed are entered there,
+and all file names in the list are examined.
+.TP
+.BI * " D " file-list
+Delete the named files from the menu.
+If no files are named, the current file is deleted.
+It is an error to
+.B D
+a modified file, but a subsequent
+.B D
+will delete such a file.
+.PD
+.SS I/O Commands
+.PD0
+.TP
+.BI * " e " filename
+Replace the file by the contents of the named external file.
+Set dot to the beginning of the file.
+.TP
+.BI r " filename
+Replace the text in the range by the contents of the named external file.
+Set dot.
+.TP
+.BI w " filename
+Write the range (default
+.BR 0,$ )
+to the named external file.
+.TP
+.BI * " f " filename
+Set the file name and print the resulting menu entry.
+.PP
+If the file name is absent from any of these, the current file name is used.
+.B e
+always sets the file name;
+.B r
+and
+.B w
+do so if the file has no name.
+.TP
+.BI < " command
+Replace the range by the standard output of the command.
+.TP
+.BI > " command
+Send the range to the standard input of the command.
+.TP
+.BI | " command
+Send the range to the standard input, and replace it by
+the standard output, of the command.
+.TP
+.BI * " cd " directory
+Change working directory.
+If no directory is specified,
+.B $home
+is used.
+.PD
+.PP
+In any of
+.BR < ,
+.BR > ,
+or
+.BR | ,
+if the
+.I command
+is omitted the last
+.I command
+(of any type) is substituted.
+.SS Loops and Conditionals
+.PD0
+.TP
+.BI x/ regexp / " command
+For each match of the regular expression in the range, run the command
+with dot set to the match.
+Set dot to the last match.
+If the regular
+expression and its slashes are omitted, 
+.L /.*\en/
+is assumed.
+Null string matches potentially occur before every character
+of the range and at the end of the range.
+.TP
+.BI y/ regexp / " command
+Like
+.BR x ,
+but run the command for each substring that lies before, between,
+or after
+the matches that would be generated by
+.BR x .
+There is no default regular expression.
+Null substrings potentially occur before every character
+in the range.
+.TP
+.BI * " X/ regexp / " command
+For each file whose menu entry matches the regular expression,
+make that the current file and
+run the command.
+If the expression is omitted, the command is run
+in every file.
+.TP
+.BI * " Y/ regexp / " command
+Same as
+.BR X ,
+but for files that do not match the regular expression,
+and the expression is required.
+.TP
+.BI g/ regexp / " command
+.br
+.ns
+.TP
+.BI v/ regexp / " command
+If the range contains
+.RB ( g )
+or does not contain
+.RB ( v )
+a match for the expression,
+set dot to the range and run the command.
+.PP
+These may be nested arbitrarily deeply, but only one instance of either
+.B X
+or
+.B Y
+may appear in a \%single command.
+An empty command in an
+.B x
+or
+.B y
+defaults to
+.BR p ;
+an empty command in
+.B X
+or
+.B Y
+defaults to
+.BR f .
+.B g
+and
+.B v
+do not have defaults.
+.PD
+.SS Miscellany
+.TF (empty)
+.TP
+.BI * " u " n
+Undo the last
+.I n
+(default 1)
+top-level commands that changed the contents or name of the
+current file, and any other file whose most recent change was simultaneous
+with the current file's change.
+Successive
+.BR u 's
+move further back in time.
+The only commands for which u is ineffective are
+.BR cd ,
+.BR u ,
+.B w
+and
+.BR D .
+If
+.I n
+is negative,
+.B u
+`redoes,' undoing the undo, going forwards in time again.
+.TP
+(empty)
+If the range is explicit, set dot to the range.
+If no address is specified (the
+command is a newline) dot is extended in either direction to
+line boundaries and printed.
+If dot is thereby unchanged, it is set to
+.B .+1 
+and printed.
+.PD
+.SS Grouping and multiple changes
+Commands may be grouped by enclosing them in braces
+.BR {} .
+Commands within the braces must appear on separate lines (no backslashes are
+required between commands).
+Semantically, an opening brace is like a command:
+it takes an (optional) address and sets dot for each sub-command.
+Commands within the braces are executed sequentially, but changes made
+by one command are not visible to other commands (see the next
+paragraph).
+Braces may be nested arbitrarily.
+.PP
+When a command makes a number of changes to a file, as in
+.BR x/re/c/text/ ,
+the addresses of all changes to the file are computed in the original file.
+If the changes are in sequence,
+they are applied to the file.
+Successive insertions at the same address are catenated into a single
+insertion composed of the several insertions in the order applied.
+.SH FILES
+.TF /appl/acme/acme/*/src
+.TP
+.B $home/acme.dump
+default file for
+.B Dump
+and
+.BR Load ;
+also where state is written if
+.I acme
+dies unexpectedly.
+.TP
+.B /acme/*/guide
+template files for applications
+.TP
+.B /acme/*/readme
+informal documentation for applications
+.TP
+.B /appl/acme/acme/*/src
+source for applications
+.TP
+.B /acme/dis
+dis files for applications
+.SH SOURCE
+.B /appl/acme
+.br
+.B /appl/acme/acme/bin/src/win.b
+.SH SEE ALSO
+.IR acme (4)
+.br
+Rob Pike,
+.IR "Acme: A User Interface for Programmers" ", Volume 2"
+.SH BUGS
+With the
+.B -l
+option or
+.B Load
+command,
+the recreation of windows under control of external programs
+such as
+.I win
+is just to rerun the command; information may be lost.