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        !            10: \begin{document}
        !            11: 
        !            12: \title{Changes to\\ The Rand MH Message Handling System:\\ MH.6}
        !            13: \author{Marshall T.~Rose\\
        !            14:        Northrop Research and Technology Center\\
        !            15:        One~Research Park\\
        !            16:        Palos Verdes Peninsula, CA  90274}
        !            17: \date{\ifdraft \versiondate/\\ Version \versiontag/\else \today\fi}
        !            18: \maketitle
        !            19: \footnotetext[0]{\hskip -\parindent
        !            20: This document (version \versiontag/)
        !            21: was \LaTeX set \today\ with \fmtname\ v\fmtversion.}%
        !            22: 
        !            23: \begin{abstract}
        !            24: \noindent This document describes the user-visible change to the
        !            25: UCI version of the Rand \MH/ system that were made from \mh5 to \mh6.
        !            26: This document does not describe bug-fixes, per se,
        !            27: or internal changes,
        !            28: unless these activities resulted in a visible change for the \MH/ user.
        !            29: 
        !            30: This document is meant to supplement,
        !            31: not supersede, the standard \MH/ User's manual\cite{MH}.
        !            32: 
        !            33: Comments concerning this documentation should be addressed to the Internet
        !            34: mailbox {\sf [email protected]}.
        !            35: \end{abstract}
        !            36: 
        !            37: \bop\pagestyle{plain}\pagenumbering{arabic}
        !            38: 
        !            39: \section*     {Acknowledgements}
        !            40: The \MH/ system described herein is based on the original Rand \MH/ system.
        !            41: It has been extensively developed (perhaps too much so) by Marshall T.~Rose
        !            42: and John L.~Romine at the University of California, Irvine.
        !            43: Einar A.~Stefferud, Jerry N.~Sweet,
        !            44: and Terry P.~Domae provided numerous suggestions
        !            45: to improve the UCI version of \MH/.
        !            46: Of course,
        !            47: a large number of people have helped \MH/ along.
        !            48: The list of ``\MH/~immortals'' is too long to list here.
        !            49: 
        !            50: \section*     {Disclaimer}
        !            51: The Regents of the University of California wish to make it known that:
        !            52: \begin{quote}
        !            53: Although each program has been tested by its contributor,
        !            54: no warranty, express or implied,
        !            55: is made by the contributor or the University of California,
        !            56: as to the accuracy and functioning of the program
        !            57: and related program material,
        !            58: nor shall the fact of distribution constitute any such warranty,
        !            59: and no responsibility is assumed by the contributor
        !            60: or the University of California in connection herewith.
        !            61: \end{quote}
        !            62: 
        !            63: \bop
        !            64: 
        !            65: \section*     {Conventions}
        !            66: In this document,
        !            67: certain \LaTeX -formatting conventions are adhered to:
        !            68: \begin{enumerate}
        !            69: \item  The names of \unix/ commands, such as \pgm{comp},
        !            70: are presented in {\it text italics}.
        !            71: 
        !            72: \item  Arguments to programs, such as \arg{msgs},
        !            73: are presented in {\tt typewriter style} and delimited by single-quotes.
        !            74: 
        !            75: \item  \unix/ pathnames and envariables,
        !            76: such as $$\file{/usr/uci/}\hbox{\qquad and\qquad}\file{\$SIGNATURE},$$
        !            77: are presented in {\sl slanted roman}.
        !            78: 
        !            79: \item  Text presenting an example, such as
        !            80: \example comp\ -editor\ zz\endexample
        !            81: is presented in {\tt typewriter style}.
        !            82: \end{enumerate}
        !            83: 
        !            84: \bop
        !            85: 
        !            86: \section*     {General Changes}
        !            87: Unlike the changes between \mh4 and \mh5,
        !            88: a large number of user-visible changes have been made in \mh6.
        !            89: These changes have been in the form of bug fixes and several generalizations.
        !            90: The majority of these will not affect novice users.
        !            91: In addition, \mh6 is a great deal faster than \mh5:
        !            92: all programs have been speeded-up significantly,
        !            93: thanks to work done by Van Jacobson as part of the process of including \mh5
        !            94: in the 4.3\bsd/~\unix/ distribution.
        !            95: 
        !            96: This document describes all user-visible changes to \mh5 from it's initial
        !            97: release to the initial release of \mh6.
        !            98: 
        !            99: \subsection*   {System-5 Support}
        !           100: In addition to support for \bsd/~\unix/, V7~\unix/ and \xenix/ variants of
        !           101: \unix/,
        !           102: \MH/ finally has support for the AT\&T variant of \unix/, System~5.
        !           103: Hopefully this will greatly expand the number of system which can run \MH/.
        !           104: Ironically,
        !           105: it appears that five ports of earlier versions of \MH/ (including \mh5)
        !           106: were done,
        !           107: but news of the work was not widespread.%
        !           108: \nfootnote{In fact,
        !           109: three groups in one large organization ported \MH/ independently,
        !           110: each without knowledge of the others' work.}
        !           111: 
        !           112: \subsection*   {Documentation}
        !           113: Several new documents have been included in the \mh6 distribution:
        !           114: The paper {\em MH.5: How to process 200 messages a day and still get some
        !           115: real work done}
        !           116: was presented at the 1985 Summer Usenix Conference and Exhibition in
        !           117: Portland, Orgeon.
        !           118: Another paper, {\em MH: A Multifarious User Agent},
        !           119: has been accepted for publication by Computer Networks.
        !           120: Both describe \MH/,
        !           121: the former from a more technical and somewhat humorous perspective,
        !           122: the latter from a more serious and research-oriented perspective.
        !           123: In addition,
        !           124: a third paper has been included,
        !           125: {\em Design of the TTI Prototype Trusted Mail Agent},
        !           126: which describes a so-called ``trusted'' mail agent built on top of \MH/.
        !           127: This paper was presented at the Second International Symposium on
        !           128: Computer Message Systems in Washington, D.C.
        !           129: A fourth paper,
        !           130: {\em MZnet: Mail Service for Personal Micro-Computer Systems},
        !           131: is also included.
        !           132: This paper,
        !           133: which was presented at the First International Symposium on Computer Message
        !           134: Systems in Nottingham, U.K.,
        !           135: describes a \cpm/-based version of \MH/.
        !           136: 
        !           137: In addition,
        !           138: the \MH/ tutorial, {\em The Rand MH Message Handling System: Tutorial},
        !           139: and,
        !           140: {\em The Rand MH Message Handling System: The UCI BBoards Facility},
        !           141: have both been updated by Jerry N.~Sweet.
        !           142: 
        !           143: For \MH/ administrators (PostMasters and the like),
        !           144: there's an entirely new document,
        !           145: {\em The Rand MH Message Handling System: Administrator's Guide}.
        !           146: It explains most of the ``ins and outs'' of maintaining an \MH/ system.
        !           147: 
        !           148: Finally, all of the manual entries and the \MH/ manual have had a thorough
        !           149: working over.
        !           150: The documentation is expanded, more accurate, and more detailed.
        !           151: 
        !           152: \subsection*   {Help Listings}
        !           153: When any \MH/ command is invoked with the \switch{help} switch,
        !           154: in addition to listing the syntax of the command and version information,
        !           155: the \MH/ configuration options will be listed.
        !           156: \MH/ has so many configuration options,
        !           157: that when debugging problems, this information is invaluable.
        !           158: 
        !           159: \subsection*   {The \MH/ Profile}
        !           160: There are two new profile entries worth noting:
        !           161: \eg{MH-Sequences} tells \MH/ the name of the file to record public
        !           162: sequences in.
        !           163: Users of \pgm{vm}, a proprietary, visual front-end to \MH/,
        !           164: make use of this to disable the public sequences feature of \MH/.
        !           165: 
        !           166: The profile entry \eg{Unseen-Sequence} names those sequences which should be
        !           167: defined as those messages recently incorporated by \pgm{inc}.
        !           168: The \pgm{show} program knows to remove messages from this sequence once it
        !           169: thinks they have been seen.
        !           170: If this profile entry is not present, or is empty, then no sequences are
        !           171: defined.
        !           172: Otherwise, for each name given, the sequence is first zero'd and then each
        !           173: message incorporated is added to the sequence.
        !           174: As such, this profile entry is rather analogous to the
        !           175: \eg{Previous-Sequence} entry in the user's \MH/ profile.
        !           176: 
        !           177: In addition, the \eg{Alternate-Mailboxes} entry in the profile has been
        !           178: expanded to support simple wild-carding.
        !           179: Also, the default for this profile entry is now the user's mail-id at any host.
        !           180: This change was made since \MH/ can no longer reliably figure out what
        !           181: the user's real outgoing address looks like.
        !           182: 
        !           183: Finally,
        !           184: when the \pgm{install-mh} program is automatically invoked by \MH/,
        !           185: it won't prompt the user for information.
        !           186: Instead, it notes that it's setting up the default environment.
        !           187: In addition,
        !           188: the \MH/ administrator may set-up a file called \file{mh.profile} in the \MH/
        !           189: library area which is consulted by \pgm{install-mh} when initializing the
        !           190: user's \profile/.
        !           191: 
        !           192: \subsection*   {The \MH/ Context}
        !           193: The \pgm{folder}, \pgm{scan}, and \pgm{show} programs have been modified to
        !           194: update the user's \MH/ context prior to writing to the user's terminal.
        !           195: This allows the \MH/ user interrupt output to the terminal and still have the
        !           196: expected context.
        !           197: This is especially useful to interrupt long \pgm{scan} listings.
        !           198: This change also introduces a subtle bug between \pgm{show} and messages
        !           199: denoted by the \eg{Unseen-Sequence}.
        !           200: See \man show(1) for the details.
        !           201: 
        !           202: \subsection*   {Addresses and 822 support}
        !           203: \MH/ now fully supports the RFC-822 routing syntax for addresses
        !           204: (it used to recognize the syntax, but ignore the information present).
        !           205: In addition,
        !           206: there are three major modes for support of non-822 addressing in \MH/:
        !           207: \begin{itemize}
        !           208: \item  BERK\hbreak
        !           209: This is useful on sites running \SendMail/.
        !           210: It doesn't support full 822--style addressing,
        !           211: in favor of recognizing such formats as ACSnet, and so on.
        !           212: For sites that can't run in an 822--compliant environment,
        !           213: this is the option to use
        !           214: (at the price of sacrificing some of the power of 822--style addressing).
        !           215: 
        !           216: \item  DUMB\hbreak
        !           217: Although not as liberal as BERK,
        !           218: the DUMB option is useful on sites in which the message transport system
        !           219: conforms to the 822 standard,
        !           220: but wants to do all the defaulting itself.
        !           221: 
        !           222: \item  BANG\hbreak
        !           223: From out in left field,
        !           224: the BANG option favors \UUCP/-style addressing over 822--style addressing.
        !           225: Hopefully when all the \UUCP/ sites around get around to adopting domain-style
        !           226: addresses, this option won't be needed.
        !           227: \end{itemize}
        !           228: 
        !           229: The \pgm{ap} program (mentioned momentarily) and the \pgm{ali} program
        !           230: both support a \switch{normalize} switch indicate if addresses should be
        !           231: resolved to their ``official'' hostnames.
        !           232: 
        !           233: \subsection*   {New Programs}
        !           234: There are five new programs available:
        !           235: The \pgm{ap} program is the \MH/ stand-alone address parser.
        !           236: It's useful for printing address in various formats
        !           237: (and for debugging address strings).
        !           238: The \pgm{dp} program is similar, but works on dates instead of addresses.
        !           239: 
        !           240: The \pgm{msgchk} program checks for new mail,
        !           241: possibly using the Post Office Protocol, POP, described below.
        !           242: 
        !           243: A new receive mail hook,
        !           244: the \pgm{rcvstore} program,
        !           245: which was written by Julian L.~Onions is available.
        !           246: 
        !           247: Finally, a visual front-end to \pgm{msh} called \pgm{vmh} has been included.
        !           248: (This program is discussed in greater detail later on.)
        !           249: 
        !           250: \subsection*   {Message Numbering}
        !           251: \MH/ now no longer restricts the number of messages which may reside in a
        !           252: folder
        !           253: (beyond that of system memory constraints).
        !           254: This means that message numbers larger than 2000 are permissible.
        !           255: Hopefully this will make life easier for people reading the network news
        !           256: using \MH/.
        !           257: 
        !           258: \section*     {The WhatNow Shell}
        !           259: In \mh6,
        !           260: there is now the concept of a unified \whatnow/ processor that
        !           261: the four composition programs, \pgm{comp}, \pgm{dist}, \pgm{forw},
        !           262: and \pgm{repl} all invoke.
        !           263: This permits a greater flexibility in building mail applications with \MH/.
        !           264: As a result, there's a new program, \pgm{whatnow}, which acts as the default
        !           265: \whatnow/ program.
        !           266: Consult the \man whatnow(1) manual entry for all the details.
        !           267: 
        !           268: The only other thing worth noting is that unless \MH/ has been compiled with
        !           269: the UCI option,
        !           270: the user's \file{\$HOME/.signature} file is not consulted for the user's
        !           271: personal name.
        !           272: 
        !           273: \section*     {Format Strings}
        !           274: A general format string facility has been added to allow \MH/ users to tailor
        !           275: the output of certain commands.
        !           276: 
        !           277: The \pgm{inc}, \pgm{scan}, \pgm{ap}, and \pgm{dp} programs all consult a
        !           278: file containing format strings.
        !           279: Format strings,
        !           280: which look a lot like \man printf(3) strings,
        !           281: give these \MH/ commands precise instructions on how to format their output.
        !           282: 
        !           283: As a result,
        !           284: the \pgm{inc} and \pgm{scan} programs no longer have the
        !           285: \switch{size}, \switch{nosize},
        !           286: \switch{time}, \switch{notime},
        !           287: \switch{numdate}, and \switch{nonumdate}
        !           288: switches.
        !           289: These switches have been replaced with the
        !           290: \switch{form~formatfile} switch and the \switch{format~string} switch.
        !           291: The former directs the program to consult the named file for the format
        !           292: strings.
        !           293: The latter directs the program to use the named string as the format.
        !           294: To get the behavior of the old \switch{time} option,
        !           295: use the \switch{form~scan.time} option.
        !           296: Similarly,
        !           297: to get the effect of \switch{size},
        !           298: use \switch{form~scan.size}.
        !           299: 
        !           300: The \pgm{repl} command uses a file containing format files to
        !           301: indicate how the reply draft should be constructed.
        !           302: Note that reply templates prior to \mh6 are incompatible with \mh5.
        !           303: Don't worry though,
        !           304: it's quite easy to convert the templates by hand.
        !           305: (Those clever enough to have written a reply template to begin with won't
        !           306: have {\em any\/} problem.)
        !           307: 
        !           308: Similarly, when the \pgm{forw} program is constructing a digest,
        !           309: it uses a file containing format strings to indicate how to build the
        !           310: encapsulating draft.
        !           311: 
        !           312: \section*     {News}
        !           313: The depreciated \MH/ news system (from \mh1) is now de-supported.
        !           314: Use the ``hoopy'' BBoards facility instead.
        !           315: 
        !           316: \section*     {BBoards}
        !           317: \MH/ maintainers take note:
        !           318: the default home directory for the bboards login has changed from
        !           319: \file{/usr/bboards/} to \file{/usr/spool/bboards/}.
        !           320: Use the \eg{bbhome} directive in your \MH/ configuration file to set
        !           321: it back to the old value if you wish.
        !           322: 
        !           323: In addition, the aliases field for a BBoard in the BBoards file is now
        !           324: deemed useful only for addressing, not for user input to \pgm{bbc}.
        !           325: This means when giving the name of a BBoard to \pgm{bbc},
        !           326: only the official name should be used.
        !           327: 
        !           328: A final note for mailsystem maintainers:
        !           329: the \MMDFII/ BBoards channel and the \SendMail/ BBoards mailer have been
        !           330: modified to use the standard message encapsulation format when returning
        !           331: failed messages to the list maintainer.
        !           332: This means that the failure notices that the maintainer receives can
        !           333: simply be \pgm{burst}.
        !           334: 
        !           335: \subsection*   {New Switches in bbc}
        !           336: The \pgm{bbc} program permits you to specify the \eg{mshproc} to use on the
        !           337: command line by using the \switch{mshproc~program} option.
        !           338: In addition, options which aren't understood by \pgm{bbc} are passed along to
        !           339: the \eg{mshproc}.
        !           340: 
        !           341: In addition, the following commands
        !           342: pass any unrecognized switches on to the program that they invoke:
        !           343: \pgm{bbc}, \pgm{next}, \pgm{show}, \pgm{prev}, and \pgm{vmh}.
        !           344: 
        !           345: \subsection*   {Distributed BBoards}
        !           346: If both BBoards and POP (see the next section) are enabled,
        !           347: then distributed BBoards can be supported on top of the POP service.
        !           348: This allows the \MH/ user to read BBoards on a server machine
        !           349: instead of the local host
        !           350: (which saves a lot of wasted disk space when the same BBoards are replicated
        !           351: several times at a site with several hosts).
        !           352: See the {\em Administrator's Guide\/} for information on how this can be made
        !           353: completely transparent to the \MH/ user.
        !           354: 
        !           355: If you have several machines at your site running 4.2\bsd/~\unix/
        !           356: and connected by an \ethernet/ (or other high-speed LAN),
        !           357: you {\em want\/} this software.
        !           358: 
        !           359: \subsection*   {Visual Front-End to msh}
        !           360: A simple window management protocol has been implemented for \MH/ programs
        !           361: that might wish to act as a back-end to a sophisticated visual front-end.
        !           362: 
        !           363: The first implementation of a server side (front-end) program is \pgm{vmh},
        !           364: which uses \man curses(3) to maintain a split-screen interface.
        !           365: Perhaps look for a \pgm{mhtool} program for the SUN next!
        !           366: 
        !           367: The \pgm{msh} program has been modified to speak the client side (back-end)
        !           368: of this protocol, if so directed.
        !           369: At present, \pgm{msh} is the only program in the \MH/ distribution which
        !           370: implements the client side of the window management protocol.
        !           371: 
        !           372: \subsection*   {Updates in msh}
        !           373: Prior to quitting,
        !           374: the \pgm{msh} command now asks if the \pgm{packf\/}'d file you've been
        !           375: perusing should be updated if you've modified it and the file is writable by
        !           376: you.
        !           377: The file can be modified by using \pgm{burst}, \pgm{rmm}, \pgm{rmm},
        !           378: or \pgm{sortm} commands.
        !           379: The file can also be modified by using the \pgm{refile} command without the
        !           380: \switch{link} option.
        !           381: (Or course,
        !           382: the \switch{link} option doesn't actually link anything to the file.)
        !           383: 
        !           384: \section*     {Distributed Mail}
        !           385: \MH/ now contains a powerful facility for doing distributed mail
        !           386: (having \MH/ reside on a host different than the message transport agent).
        !           387: For general information,
        !           388: consult either the 
        !           389: {\em MH.5: How to process 200 messages a day and still get some real work
        !           390: done} paper,
        !           391: or the {\em MH: A Multifarious User Agent} paper.
        !           392: For specific information,
        !           393: consult the {\em Administrator's Guide}.
        !           394: Here's a brief synopsis:
        !           395: 
        !           396: This POP facility in \MH/ is based on a modification of the ARPA Post
        !           397: Office Protocol (POP).
        !           398: A POP {\em subscriber\/} is a remote user,
        !           399: on a POP {\em client host},
        !           400: that wishes to pick-up mail on a POP {\em service host}.
        !           401: 
        !           402: There are two ways to administer POP:
        !           403: \begin{itemize}
        !           404: \item  Naive Mode\hbreak
        !           405: Each user-id in the \man passwd(5) file is considered a POP subscriber.
        !           406: No changes are required for the mailsystem on the POP service host.
        !           407: However,
        !           408: this method requires that each POP subscriber have an entry in the password
        !           409: file.
        !           410: The POP server will fetch the user's mail from wherever maildrops are kept on
        !           411: the POP service host.
        !           412: This means that if maildrops are kept in the user's home directory,
        !           413: then each POP subscriber must have a home directory.
        !           414: 
        !           415: \item  Smart Mode\hbreak
        !           416: This is based on the notion that the list of POP subscribers and the list of
        !           417: login users are completely separate name spaces.
        !           418: A separate database (similar to the \man BBoards(5) file)
        !           419: is used to record information about each POP subscriber.
        !           420: Unfortunately,
        !           421: the local mailsystem must be changed to reflect this.
        !           422: This requires two changes (both of which are simple):
        !           423: \begin{enumerate}
        !           424: \item  Aliasing\hbreak
        !           425:        The aliasing mechanism is augmented so that POP subscriber addresses
        !           426:        are diverted to a special delivery mechanism.
        !           427:        \MH/ comes with a program, \man popaka(8), which generates the
        !           428:        additional information to be put in the mailsystem's alias file.
        !           429: \item  Delivery\hbreak
        !           430:        A special POP channel (for \MMDFII/) or POP mailer (for \SendMail/)
        !           431:        performs the actual delivery (\mh6 supplies both).
        !           432:        All it really does is just place the mail in the POP spool area.
        !           433: \end{enumerate}
        !           434: Clever mailsystem people will note that
        !           435: the POP mechanism is really a special case of the more general
        !           436: BBoards mechanism.
        !           437: \end{itemize}
        !           438: These two different philosophies are not compatible on the same POP service
        !           439: host: one or the other, but not both, may be run.
        !           440: 
        !           441: In addition, there is one user-visible difference,
        !           442: which the administrator controls the availability of.
        !           443: The difference is whether the POP subscriber must supply a password to the POP
        !           444: server:
        !           445: \begin{itemize}
        !           446: \item  ARPA standard method\hbreak
        !           447: This uses the standard ARPA technique of sending a username and a password.
        !           448: The appropriate programs (\pgm{inc}, \pgm{msgchk}, and possibly \pgm{bbc\/})
        !           449: will prompt the user for this information.
        !           450: 
        !           451: \item  \unix/ remote method\hbreak
        !           452: This uses the Berkeley \unix/ reserved port method for authentication.
        !           453: This requires that the two or three mentioned above programs be {\em setuid\/}
        !           454: to root.
        !           455: (There are no known holes in any of these programs.)
        !           456: \end{itemize}
        !           457: These two different philosophies are compatible on the same POP service host:
        !           458: to selectively disable RPOP for hosts which aren't trusted,
        !           459: either modify the \file{.rhosts} file in the case of POP subscribers being
        !           460: \unix/ logins,
        !           461: or zero the contents of network address field of the \man pop(5) file for the
        !           462: desired POP subscribers.
        !           463: 
        !           464: The \pgm{inc} command also has two other switches when \MH/ is enabled for
        !           465: POP:
        !           466: \switch{pack~file} and \switch{nopack}.
        !           467: Normally,
        !           468: \pgm{inc} will use the POP to incorporate mail from a POP service host into
        !           469: an \MH/ folder (\eg{+inbox}).
        !           470: However,
        !           471: there are some misguided individuals who prefer to \pgm{msh} to read their
        !           472: maildrop.
        !           473: By using the \switch{pack~file} option,
        !           474: these individuals can direct \pgm{inc} to fetch their maildrop from the POP
        !           475: service host and store it locally in the named file.
        !           476: As expected, \pgm{inc} will treat the local file as a maildrop,
        !           477: performing the appropriate locking protocols.
        !           478: 
        !           479: \section*     {Rcvmail hooks}
        !           480: In order to offer users of \MH/ increated rcvmail hook functionality,
        !           481: the \pgm{slocal} program has been upgraded to support the semantics of
        !           482: the \MMDFII/ mail-delivery mechanism.
        !           483: This means that users of \mh6 can maintain identical \file{.maildelivery}
        !           484: files regardless of the underlying transport system.
        !           485: See \man mhook(1) for all the details.
        !           486: 
        !           487: \subsection*   {Field change in rcvpack}
        !           488: The \pgm{rcvpack} rcvmail hook now adds the field name \eg{Delivery-Date:}
        !           489: instead of \eg{Cron-Date:} to messages it \pgm{pack\/}s.
        !           490: 
        !           491: \section*     {Other Changes}
        !           492: Here's the miscellany:
        !           493: 
        !           494: \subsection*   {Continuation Lines}
        !           495: Alias files used by \MH/,
        !           496: display templates used by \pgm{mhl},
        !           497: and format files used by \pgm{forw}, \pgm{repl}, and \pgm{scan} all support
        !           498: a standard continuation line syntax.
        !           499: To continue a line in one of these files,
        !           500: simply end the line with the backslash character (`$\backslash$').
        !           501: All the other files used by \MH/ are in 822--format,
        !           502: so the 822--continuation mechanism is used.%
        !           503: \nfootnote{Looking back,
        !           504: it would have been best had all files in \MH/ used the 822--format.}
        !           505: 
        !           506: \subsection*   {Modifications to show}
        !           507: The \switch{format}, \switch{noformat}, \switch{pr}, and \switch{nopr}
        !           508: options to \pgm{show} have gone away in favor of a more general mechanism.
        !           509: The \switch{showproc~program} option tells \pgm{show}
        !           510: (or \pgm{next} or \pgm{prev\/}) to use the named program as the \eg{showproc}.
        !           511: The \switch{noshowproc} option tells \pgm{show}, et. al.,
        !           512: to use the \man cat(1) program instead of a \eg{showproc}.
        !           513: As a result, the profile entry \eg{prproc} is no longer used.
        !           514: 
        !           515: \subsection*   {Front-End to mhl}
        !           516: When outputting to a terminal,
        !           517: the \pgm{mhl} program now runs the program denoted by the profile entry
        !           518: \eg{moreproc}.
        !           519: If this entry is not present,
        !           520: the default is the UCB \pgm{more} program.
        !           521: If the entry is non-empty,
        !           522: then that program is spliced between \pgm{mhl} and the user's terminal.
        !           523: The author uses the \pgm{less} program as his \eg{moreproc}.
        !           524: 
        !           525: Of course,
        !           526: if \pgm{mhl} isn't outputting to a terminal,
        !           527: then \eg{moreproc} is not invoked.
        !           528: 
        !           529: \subsection*   {Switch change in inc}
        !           530: The \switch{ms~ms-file} switch in \pgm{inc} has been changed to
        !           531: \switch{file~name} to be more consistent.
        !           532: 
        !           533: \subsection*   {Complex Expressions in pick}
        !           534: The \pgm{pick} command now handles complex boolean expressions.
        !           535: 
        !           536: \subsection*   {Defaults change in prompter and burst}
        !           537: The \switch{prepend} option is now the default in \pgm{prompter}.
        !           538: The \switch{noinplace} option is now the default in \pgm{burst}.
        !           539: 
        !           540: \subsection*   {Interactive option in rmf}
        !           541: The \pgm{rmf} program has been changed to support an \switch{interactive}
        !           542: switch.
        !           543: If given,
        !           544: then the user is prompted regarding whether the folder should be deleted.
        !           545: If the folder to be removed is not given by the user,
        !           546: this switch is defaulted to on.
        !           547: 
        !           548: \subsection*   {Trusted Mail Interface}
        !           549: \MH/ now has an interface for so-called ``trusted mail'' applications.
        !           550: Although the modifications to \MH/ to support this are in the public domain,
        !           551: the actual library that \MH/ uses is not.
        !           552: Contact Professor David J.~Farber ({\sf Farber@UDel\/}) for more information.
        !           553: 
        !           554: \bibliography{mh6}
        !           555: 
        !           556: \showsummary
        !           557: 
        !           558: \end{document}

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