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Annotation of 43BSDReno/share/doc/usd/24.troff/m3, revision 1.1

1.1     ! root        1: .\"    @(#)m3  6.2 (Berkeley) 4/17/86
        !             2: .\"
        !             3: .tr |
        !             4: .rm mx
        !             5: .mh
        !             6: Tabs, Leaders, and Fields
        !             7: .sc
        !             8: Tabs and leaders.
        !             9: The \s-1ASCII\s+1 horizontal tab character and the \s-1ASCII\s+1
        !            10: \s-1SOH\s+1 (hereafter known as the \fIleader\fR character)
        !            11: can both be used to generate either horizontal motion or
        !            12: a string of repeated characters.
        !            13: The length of the generated entity is governed
        !            14: by internal \fItab stops\fR specifiable
        !            15: with \fBta\fR.
        !            16: The default difference is that tabs generate motion and leaders generate
        !            17: a string of periods;
        !            18: \fBtc\fR and \fBlc\fR
        !            19: offer the choice of repeated character or motion.
        !            20: There are three types of internal tab stops\(em\
        !            21: \fIleft\fR adjusting, \fIright\fR adjusting,
        !            22: and \fIcentering\fR.
        !            23: In the following table:
        !            24: \fID\fR is the distance from the current position on the \fIinput\fR line
        !            25: (where a tab or leader was found)
        !            26: to the next tab stop;
        !            27: \fInext-string\fR consists
        !            28: of the input characters following the tab (or leader) up to the next tab (or leader) or end of line;
        !            29: and
        !            30: \fIW\fR is the width of \fInext-string\fR.
        !            31: .TS
        !            32: center box;
        !            33: c2|c2|c
        !            34: c2|c2|c
        !            35: c2|c2|l.
        !            36: Tab    Length of motion or     Location of
        !            37: type   repeated characters     \fInext-string\fR
        !            38: _
        !            39: Left   \fID\fR Following \fID\fR
        !            40: Right  \fID\-W\fR      Right adjusted within \fID\fR
        !            41: Centered       \fID\-W\(sl\fR2 Centered on right end of \fID\fR
        !            42: .TE
        !            43: The length of generated motion is allowed to be negative, but
        !            44: that of a repeated character string cannot be.
        !            45: Repeated character strings contain an integer number of characters, and
        !            46: any residual distance is prepended as motion.
        !            47: Tabs or leaders found after the last tab stop are ignored, but may be used
        !            48: as \fInext-string\fR terminators.
        !            49: .pg
        !            50: Tabs and leaders are not interpreted in \fIcopy mode\fR.
        !            51: \fB\et\fR and \fB\ea\fR always generate a non-interpreted
        !            52: tab and leader respectively, and
        !            53: are equivalent to actual tabs and leaders in \fIcopy mode\fR.
        !            54: .sc
        !            55: Fields.
        !            56: A \fIfield\fR is contained between
        !            57: a \fIpair\fR of \fIfield delimiter\fR characters,
        !            58: and consists of sub-strings
        !            59: separated by \fIpadding\fR indicator characters.
        !            60: The field length is the distance on the
        !            61: \fIinput\fR line from the position where the field begins to the next tab stop.
        !            62: The difference between the total length of all the sub-strings
        !            63: and the field length is incorporated as horizontal
        !            64: padding space that is divided among the indicated
        !            65: padding places.
        !            66: The incorporated padding is allowed to be negative.
        !            67: For example,
        !            68: if the field delimiter is \fB#\fR and the padding indicator is \fB^\fR,
        !            69: \fB#^\fIxxx\fB^\fIright\|\fB#\fR
        !            70: specifies a right-adjusted string with the string \fIxxx\fR centered
        !            71: in the remaining space.
        !            72: .h1
        !            73: .bt
        !            74: \fB&ta\fI|Nt|...\fR    8n;|0.5in       none    E,\fBm\fR       \
        !            75: Set tab stops and types.
        !            76: \fIt=\fBR\fR, right adjusting;
        !            77: \fIt=\fBC\fR, centering;
        !            78: \fIt\fR absent, left adjusting.
        !            79: \*(TR tab stops are preset every 0.5in.;
        !            80: \*(NR every 8 character widths.
        !            81: The stop values are separated by spaces, and
        !            82: a value preceded by \fB+\fR
        !            83: is treated as an increment to the previous stop value.
        !            84: .bt
        !            85: \fB&tc\fI|c\fR none    none    E       \
        !            86: The tab repetition character becomes \fIc\fR,
        !            87: or is removed specifying motion.
        !            88: .bt
        !            89: \fB&lc\fI|c\fR \fB.\fR none    E       \
        !            90: The leader repetition character becomes \fIc\fR,
        !            91: or is removed specifying motion.
        !            92: .bt
        !            93: \fB&fc\fI|a|b\fR       off     off     -       \
        !            94: The field delimiter is set to \fIa\fR;
        !            95: the padding indicator is set to the \fIspace\fR character or to
        !            96: \fIb\fR, if given.
        !            97: In the absence of arguments the field mechanism is turned off.
        !            98: .mh
        !            99: Input and Output Conventions and Character Translations
        !           100: .sc
        !           101: Input character translations.
        !           102: Ways of inputting the graphic character set were
        !           103: discussed in \(sc2.1.
        !           104: The \s-1ASCII\s+1 control characters horizontal tab (\(sc9.1),
        !           105: \s-1SOH\s+1 (\(sc9.1), and backspace (\(sc10.3) are discussed elsewhere.
        !           106: The newline delimits input lines.
        !           107: In addition,
        !           108: \s-1STX\s+1, \s-1ETX\s+1, \s-1ENQ\s+1, \s-1ACK\s+1, and \s-1BEL\s+1
        !           109: are accepted,
        !           110: and may be used as delimiters or translated into a graphic with \fBtr\fR (\(sc10.5).
        !           111: \fIAll\fR others are ignored.
        !           112: .pg
        !           113: The \fIescape\fR character \fB\e\fR
        !           114: introduces \fIescape sequences\fR\(em\
        !           115: causes the following character to mean
        !           116: another character, or to indicate
        !           117: some function.
        !           118: A complete list of such sequences is given in the Summary and Index on page 6.
        !           119: \fB\e\fR
        !           120: should not be confused with the \s-1ASCII\s+1 control character \s-1ESC\s+1 of the
        !           121: same name.
        !           122: The escape character \fB\e\fR can be input with the sequence \fB\e\e\fR.
        !           123: The escape character can be changed with \fBec\fR,
        !           124: and all that has been said about the default \fB\e\fR becomes true
        !           125: for the new escape character.
        !           126: \fB\ee\fR can be used to print whatever the current escape character is.
        !           127: If necessary or convenient, the escape mechanism may be turned off with \fBeo\fR,
        !           128: and restored with \fBec\fR.
        !           129: .h1
        !           130: .bt
        !           131: \fB&ec\fI|c\fR \fB\e\fR        \fB\e\fR        -       \
        !           132: Set escape character to \fB\e\fR, or to \fIc\fR, if given.
        !           133: .bt
        !           134: \fB&eo\fR      on      -       -       Turn escape mechanism off.
        !           135: .sc
        !           136: Ligatures.
        !           137: .lg0
        !           138: Five ligatures are available
        !           139: in the current \*(TR character set \(em
        !           140: \fB\(fi\fR, \fB\(fl\fR, \fB\(ff\fR, \fB\(Fi\fR, and \fB\(Fl\fR.
        !           141: They may be input (even in \*(NR) by
        !           142: \fB\e(fi\fR, \fB\e(fl\fR, \fB\e(ff\fR, \fB\e(Fi\fR, and \fB\e(Fl\fR respectively.
        !           143: .lg
        !           144: The ligature mode is normally on in \*(TR, and \fIautomatically\fR invokes 
        !           145: ligatures during input.
        !           146: .h1
        !           147: .bt
        !           148: \fB&lg\fI|N\fR off;|on on      -       Ligature mode
        !           149: is turned on if \fIN\fR is absent or non-zero,
        !           150: and turned off if \fIN\(eq\^\fR0.
        !           151: If \fIN\fR\(eq\^2, only the two-character ligatures are automatically invoked.
        !           152: Ligature mode is inhibited for
        !           153: request, macro, string, register, or file names,
        !           154: and in \fIcopy mode\fR.
        !           155: No effect in \*(NR.
        !           156: .sc
        !           157: Backspacing, underlining, overstriking, etc.
        !           158: Unless in \fIcopy mode\fR, the \s-1ASCII\s+1 backspace character is replaced
        !           159: by a backward horizontal motion having the width of the
        !           160: space character.
        !           161: Underlining as a form of line-drawing is discussed in \(sc12.4.
        !           162: A generalized overstriking function is described in \(sc12.1.
        !           163: .pg
        !           164: \*(NR automatically underlines
        !           165: characters in the \fIunderline\fR font,
        !           166: specifiable with \fBuf\fR,
        !           167: normally Times Italic on font position 2 (see \(sc2.2).
        !           168: In addition to \fBft\fR and \fB\ef\fIF\fR,
        !           169: the underline font may be selected by \fBul\fR and \fBcu\fR.
        !           170: Underlining is restricted to an output-device-dependent
        !           171: subset of \fIreasonable\fR characters.
        !           172: .h1
        !           173: .bt
        !           174: \fB&ul\fI|N\fR off     \fIN\(eq\fR1    E       \
        !           175: Underline in \*(NR (italicize in \*(TR) the next \fIN\fR
        !           176: input text lines.
        !           177: Actually, switch to \fIunderline\fR font, saving the
        !           178: current font for later restoration;
        !           179: \fIother\fR font changes within the span of a \fBul\fR
        !           180: will take effect,
        !           181: but the restoration will undo the last change.
        !           182: Output generated by \fBtl\fR (\(sc14) \fIis\fR affected by the
        !           183: font change, but does \fInot\fR decrement \fIN\fR.
        !           184: If \fIN\fR\^>\^1, there is the risk that
        !           185: a trap interpolated macro may provide text
        !           186: lines within the span;
        !           187: environment switching can prevent this.
        !           188: .bt
        !           189: \fB&cu\fI|N\fR off     \fIN\(eq\fR1    E       \
        !           190: A variant of \fBul\fR that causes \fIevery\fR character to be underlined in \*(NR.
        !           191: Identical to \fBul\fR in \*(TR.
        !           192: .bt
        !           193: \fB&uf\fI|F\fR Italic  Italic  -       \
        !           194: Underline font set to \fIF\fR.
        !           195: In \*(NR,
        !           196: \fIF\fR may \fInot\fR be on position 1 (initially Times Roman).
        !           197: .sc
        !           198: Control characters.
        !           199: Both the control character \fB.\fR and the \fIno-break\fR
        !           200: control character \fB\'\fR may be changed, if desired.
        !           201: Such a change must be compatible with the design
        !           202: of any macros used in the span of the change,
        !           203: and
        !           204: particularly of any trap-invoked macros.
        !           205: .h1
        !           206: .bt
        !           207: \fB&cc\fI|c\fR \fB.\fR \fB.\fR E       \
        !           208: The basic control character is set to \fIc\fR,
        !           209: or reset to "\fB.\fR".
        !           210: .bt
        !           211: \fB&c2\fI|c\fR \fB\'   \'\fR   E       The \fInobreak\fR control character is set
        !           212: to \fIc\fR, or reset to "\fB\'\fR".
        !           213: .sc
        !           214: Output translation.
        !           215: One character can be made a stand-in for another character using \fBtr\fR.
        !           216: All text processing (e. g. character comparisons) takes place
        !           217: with the input (stand-in) character which appears to have the width of the final
        !           218: character.
        !           219: The graphic translation occurs at the moment of output
        !           220: (including diversion).
        !           221: .h1
        !           222: .bt
        !           223: \fB&tr\fI|abcd....\fR  none    -       O       Translate \
        !           224: \fIa\fR into \fIb\fR, \fIc\fR into \fId\fR, etc.
        !           225: If an odd number of characters is given,
        !           226: the last one will be mapped into the space character.
        !           227: To be consistent, a particular translation
        !           228: must stay in effect from \fIinput\fR to \fIoutput\fR time.
        !           229: .sc
        !           230: Transparent throughput.
        !           231: An input line beginning with a \fB\e!\fR is read in \fIcopy mode\fR and \fItransparently\fR output
        !           232: (without the initial \fB\e!\fR);
        !           233: the text processor is otherwise unaware of the line's presence.
        !           234: This mechanism may be used to pass control information to a post-processor
        !           235: or to imbed control lines in a macro created by a diversion.
        !           236: .sc
        !           237: Comments and concealed newlines.
        !           238: An uncomfortably long input line that must stay
        !           239: one line (e. g. a string definition, or nofilled text)
        !           240: can be split into many physical lines by ending all but
        !           241: the last one with the escape \fB\e\fR.
        !           242: The sequence \fB\e\fR(newline) is \fIalways\fR ignored\(em\
        !           243: except in a comment.
        !           244: Comments may be imbedded at the \fIend\fR of any line by
        !           245: prefacing them with \fB\e"\fR.
        !           246: The newline at the end of a comment cannot be concealed.
        !           247: A line beginning with \fB\e"\fR will appear as a blank line and
        !           248: behave like \fB.sp|1\fR;
        !           249: a comment can be on a line by itself by beginning the line with \fB.\e"\fR.
        !           250: .mh
        !           251: Local Horizontal and Vertical Motions, and the Width Function
        !           252: .sc
        !           253: Local Motions.
        !           254: The functions \fB\ev\'\fIN\fB\|\'\fR and
        !           255: \fB\eh\'\fIN\fB\|\'\fR
        !           256: can be used for \fIlocal\fR vertical and horizontal motion respectively.
        !           257: The distance \fIN\fR may be negative; the \fIpositive\fR directions
        !           258: are \fIrightward\fR and \fIdownward\fR.
        !           259: A \fIlocal\fR motion is one contained \fIwithin\fR a line.
        !           260: To avoid unexpected vertical dislocations, it is necessary that
        !           261: the \fInet\fR vertical local motion within a word in filled text
        !           262: and otherwise within a line balance to zero.
        !           263: The above and certain other escape sequences providing local motion are
        !           264: summarized in the following table.
        !           265: .tr ||
        !           266: .ds X \0\0\0
        !           267: .TS
        !           268: center box;
        !           269: c2|cs2||c2|cs2
        !           270: c1|c2c2||c2|c2c2.
        !           271: Vertical       Effect in       Horizontal      Effect in
        !           272: Local Motion   \*(TR   \*(NR   Local Motion    \*(TR   \*(NR
        !           273: _
        !           274: .sp.4
        !           275: .TC
        !           276: l2|ls2||l2|ls2.
        !           277: \fB\*X\ev\'\fIN\|\^\fB\'\fR    Move distance \fIN\fR   \
        !           278: \fB\*X\eh\'\fIN\|\^\fB\'\fR    Move distance \fIN\fR
        !           279: .TC
        !           280: _2|_2_2||l2|ls2.
        !           281:                        \fB\*X\e\fR(space)      Unpaddable space-size space
        !           282: .TC
        !           283: l2|l2|l2||l2|ls2.
        !           284: \fB\*X\eu\fR   \(12 em up      \(12 line up    \fB\*X\e0\fR    Digit-size space
        !           285: .TC
        !           286: l2|l2|l2||_2|_2_2.
        !           287: \fB\*X\ed\fR   \(12 em down    \(12 line down                  
        !           288: .TC
        !           289: l2|l2|l2||l2|l2|l2.
        !           290: \fB\*X\er\fR   1 em up 1 line up       \fB\*X\e\||\fR  1\(sl6 em space ignored
        !           291:                        \fB\*X\e^\fR    1\(sl12 em space        ignored
        !           292: .sp.4
        !           293: .TE
        !           294: .rm X
        !           295: .tr |
        !           296: As an example,
        !           297: \fBE\s-2\v'-.4m'2\v'.4m'\s+2\fR
        !           298: could be generated by the sequence
        !           299: \fBE\es\-2\ev\'\-0.4m\'2\ev\'0.4m\'\es+2\fR;
        !           300: it should be noted in this example that
        !           301: the 0.4|em vertical motions are at the smaller size.
        !           302: .sc
        !           303: Width Function.
        !           304: The \fIwidth\fR function \fB\ew\'\fIstring\fB\|\'\fR
        !           305: generates the numerical width of \fIstring\fR (in basic units).
        !           306: Size and font changes may be safely imbedded in \fIstring\fR,
        !           307: and will not affect the current environment.
        !           308: For example,
        !           309: \&\fB.ti|\-\\w\'1.|\'u\fR could be used to
        !           310: temporarily indent leftward a distance equal to the
        !           311: size of the string "\fB1.|\fR".
        !           312: .pg
        !           313: The width function also sets three number registers.
        !           314: The registers \fBst\fR and \fBsb\fR are set respectively to the highest and
        !           315: lowest extent of \fIstring\fR relative to the baseline;
        !           316: then, for example,
        !           317: the total \fIheight\fR of the string is \fB\en(stu\-\en(sbu\fR.
        !           318: In \*(TR the number register \fBct\fR is set to a value
        !           319: between 0|and|3:
        !           320: 0 means that all of the characters in \fIstring\fR were short lower
        !           321: case characters without descenders (like \fBe\fR);
        !           322: 1 means that at least one character has a descender (like \fBy\fR);
        !           323: 2 means that at least one character is tall (like \fBH\fR);
        !           324: and 3 means that both tall characters and characters with
        !           325: descenders are present.
        !           326: .sc
        !           327: Mark horizontal place.
        !           328: The escape sequence \fB\ek\fIx\fR will cause the \fIcurrent\fR horizontal
        !           329: position in the \fIinput line\fR to be stored in register \fIx\fR.
        !           330: As an example,
        !           331: the construction \fB\ekx\fIword\|\fB\eh\'\|~\|\enxu+2u\'\fIword\fB\fR
        !           332: will embolden \fIword\fR by backing up to almost its beginning and overprinting it,
        !           333: resulting in \kz\fIword\fR\h'|\nzu+2u'\fIword\fR.
        !           334: .mh
        !           335: Overstrike, Bracket, Line-drawing, and Zero-width Functions
        !           336: .sc
        !           337: Overstriking.
        !           338: Automatically centered overstriking of up to nine characters
        !           339: is provided by the \fIoverstrike\fR function
        !           340: \fB\eo\'\fIstring\fB\|\'\fR.
        !           341: The characters in \fIstring\fR are overprinted with centers aligned; the total width
        !           342: is that of the widest character.
        !           343: \fIstring\fR should \fInot\fR contain local vertical motion.
        !           344: As examples,
        !           345: \fB\eo\'e\e\'\'\fR produces \fB\o'e\''\fR, and
        !           346: \fB\eo\'\e(mo\e(sl\'\fR produces \fB\o'\(mo\(sl'\fR.
        !           347: .sc
        !           348: Zero-width characters.
        !           349: The function \fB\ez\fIc\fR will output \fIc\fR without spacing over
        !           350: it, and can be used to produce left-aligned overstruck
        !           351: combinations.
        !           352: As examples,
        !           353: \fB\ez\e(ci\e(pl\fR will produce \fB\z\(ci\(pl\fR, and
        !           354: \fB\e(br\ez\e(rn\e(ul\e(br\fR will produce the smallest possible
        !           355: constructed box \fB\(br\z\(rn\(ul\(br\fR\|.
        !           356: .sc
        !           357: Large Brackets.
        !           358: The Special Mathematical Font contains a number of bracket construction pieces
        !           359: (\|\|\|\(lt\|\|\|\(lb\|\|\|\(rt\|\|\|\(rb\|\|\|\(lk\|\|\|\(rk\|\|\|\(bv\|\|\|\(lf\|\|\|\(rf\|\|\|\(lc\|\|\|\(rc\|\|)
        !           360: that can be combined into various bracket styles.
        !           361: The function \fB\eb\'\fIstring\fB\|\'\fR may be used to pile
        !           362: up vertically the characters in \fIstring\fR
        !           363: (the first character on top and the last at the bottom);
        !           364: the characters are vertically separated by 1|em and the total
        !           365: pile is centered 1\(sl2\|em above the current baseline
        !           366: (\(12 line in \*(NR).
        !           367: For example,
        !           368: \fB\eb\'\|\e(lc\e(lf\|\'E\e\|~\|\eb\'\|\e(rc\e(rf\|\'\|\ex\'\|\-0.5m\'\|\ex\'0.5m\'\|\fR
        !           369: produces
        !           370: \x'-.5m'\x'.5m'\fB\b'\(lc\(lf'E\|\b'\(rc\(rf'\fR.
        !           371: .sc
        !           372: Line drawing.
        !           373: .tr &&
        !           374: The function \fB\e\|l\|\'\fINc\fB\|\'\fR will draw a string of repeated \fIc\fR\|'s towards the right for a distance \fIN\fR.
        !           375: (\|\fB\el\fR is \fB\e\fR(lower case L).
        !           376: If \fIc\fR looks like a continuation of
        !           377: an expression for \fIN\fR, it may insulated from \fIN\fR with a \fB\e&\fR.
        !           378: If \fIc\fR is not specified, the \fB\(ru\fR (baseline rule) is used
        !           379: (underline character in \*(NR).
        !           380: If \fIN\fR is negative, a backward horizontal motion
        !           381: of size \fIN\fR is made \fIbefore\fR drawing the string.
        !           382: Any space resulting from \fIN\fR\|\(sl(size of \fIc\fR) having a remainder is put at the beginning (left end)
        !           383: of the string.
        !           384: In the case of characters
        !           385: that are designed to be connected such as
        !           386: baseline-rule\ \fB\(ru\fR\|,
        !           387: underrule\ \fB\(ul\fR\|,
        !           388: and
        !           389: root-en\ \fB\(rn\fR\|,
        !           390: the remainder space is covered by over-lapping.
        !           391: If \fIN\fR is \fIless\fR than the width of \fIc\fR,
        !           392: a single \fIc\fR is centered on a distance \fIN\fR.
        !           393: As an example, a macro to underscore a string can be written
        !           394: .br
        !           395: .tr &.
        !           396: .x1
        !           397: .ftB
        !           398: .ne 2.1
        !           399: &de us
        !           400: \e\e$1\e\|l\|\'\|~\|0\e(ul\'
        !           401: &&
        !           402: .ftR
        !           403: .x2
        !           404: .ne2.1
        !           405: .de xu
        !           406: \\$1\l'|0\(ul'
        !           407: ..
        !           408: or one to draw a box around a string
        !           409: .x1
        !           410: .ftB
        !           411: &de bx
        !           412: \e(br\e\|~\|\e\e$1\e\|~\|\e(br\e\|l\|\'\|~\|0\e(rn\'\e\|l\|\'\|~\|0\e(ul\'
        !           413: &&
        !           414: .ftR
        !           415: .x2
        !           416: .de bx
        !           417: \(br\|\\$1\|\(br\l'|0\(rn'\l'|0\(ul'
        !           418: ..
        !           419: such that
        !           420: .x1
        !           421: .ftB
        !           422: &us "underlined words"
        !           423: .ftR
        !           424: .x2
        !           425: and
        !           426: .x1
        !           427: .ftB
        !           428: &bx "words in a box"
        !           429: .ftR
        !           430: .x2
        !           431: yield
        !           432: .xu "underlined words"
        !           433: and
        !           434: .bx "words in a box"
        !           435: \h'-\w'.'u'.
        !           436: .pg
        !           437: The function \fB\eL\'\|\fINc\fB\|\'\fR will draw a vertical line consisting
        !           438: of the (optional) character \fIc\fR stacked vertically apart 1\|em
        !           439: (1 line in \*(NR),
        !           440: with the first two characters overlapped,
        !           441: if necessary, to form a continuous line.
        !           442: The default character is the \fIbox rule\fR |\(br| (\fB\|\e(br\fR);
        !           443: the other suitable character is the \fIbold vertical\fR \|\(bv\| (\fB\|\e(bv\fR).
        !           444: The line is begun without any initial motion relative to the
        !           445: current base line.
        !           446: A positive \fIN\fR specifies a line drawn downward and
        !           447: a negative \fIN\fR specifies a line drawn upward.
        !           448: After the line is drawn \fIno\fR compensating
        !           449: motions are made;
        !           450: the instantaneous baseline is at the \fIend\fR of the line.
        !           451: .pg
        !           452: .de eb
        !           453: .sp -1
        !           454: .nf
        !           455: \h'-.5n'\L'|\\nzu-1'\l'\\n(.lu+1n\(ul'\L'-|\\nzu+1'\l'|0u-.5n\(ul'
        !           456: .fi
        !           457: ..
        !           458: .ne 2i
        !           459: .mk z
        !           460: The horizontal and vertical line drawing functions may be used
        !           461: in combination to produce large boxes.
        !           462: The zero-width \fIbox-rule\fR and the \(12-em wide \fIunderrule\fR
        !           463: were \fIdesigned\fR to form corners when using 1-em vertical
        !           464: spacings.
        !           465: For example the macro
        !           466: .x1
        !           467: .ftB
        !           468: \&.de eb
        !           469: \&.sp \-1      \e"compensate for next automatic base-line spacing
        !           470: \&.nf  \e"avoid possibly overflowing word buffer
        !           471: .tr ||
        !           472: \&\eh\'\-.5n\'\eL\'\||\|\e\enau\-1\'\el\'\e\en(.lu+1n\e(ul\'\eL\'\-\||\|\e\enau+1\'\el\'\||\|0u\-.5n\e(ul\'    \e"draw box
        !           473: .tr |
        !           474: .lg0
        !           475: \&.fi
        !           476: .lg
        !           477: \&..
        !           478: .ftR
        !           479: .x2
        !           480: will draw a box around some text whose beginning vertical place was
        !           481: saved in number register \fIa\fR
        !           482: (e. g. using \fB.mk|a\fR)
        !           483: as done for this paragraph.
        !           484: .eb

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