/share/doc/usd/22.trofftut/tt05

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 42.\" $FreeBSD$
 43.\"
 44.NH
 45Tabs
 46.PP
 47Tabs
 48(the \s8ASCII\s0 `horizontal tab' character)
 49can be used to produce output in columns,
 50or to set the horizontal position of output.
 51Typically
 52tabs are used only in unfilled text.
 53Tab stops are set by default every half inch from the
 54current indent,
 55but
 56can be changed by the
 57.BD .ta
 58command.
 59To set stops every inch, for example,
 60.P1
 61^ta 1i 2i 3i 4i 5i 6i
 62.P2
 63.PP
 64Unfortunately the stops are left-justified only
 65(as on a typewriter),
 66so lining up columns of right-justified numbers can be painful.
 67If you have many numbers,
 68or if you need more complicated table layout,
 69.ul
 70don't
 71use
 72.UL troff 
 73directly;
 74use the
 75.UL tbl
 76program described in [3].
 77.PP
 78For a handful of numeric columns, you can do it this way:
 79Precede every number by enough blanks to make it line up
 80when typed.
 81.P1
 82^nf
 83^ta 1i 2i 3i
 84\0\01\0\fItab\fR\0\0\02\0\fItab\fR\0\0\03
 85\040\0\fItab\fR\0\050\0\fItab\fR\0\060
 86700\0\fItab\fR\0800\0\fItab\fR\0900
 87^fi
 88.P2
 89Then change each leading blank into the string
 90.BD \e0 .
 91This is a character that does not print, but that has
 92the same width as a digit.
 93When printed, this will produce
 94.P1
 95.ta 1i 2i 3i
 96\0\01	\0\02	\0\03
 97\040	\050	\060
 98700	800	900
 99.P2
100.PP
101It is also possible to fill up tabbed-over space with
102some character other than blanks by setting the `tab replacement character'
103with the
104.BD .tc
105command:
106.P1
107^ta 1.5i 2.5i
108^tc \e(ru	(\e(ru is "\(ru")
109Name \fItab\fR Age \fItab\fR 
110.P2
111produces
112.P1 3
113.ta 1.5i 2.5i
114.tc \(ru
115Name	 Age 	
116.tc
117.P2
118To reset the tab replacement character to a blank, use
119.BD .tc
120with no argument.
121(Lines can also be drawn with the
122.BD \el
123command, described in Section 6.)
124.PP
125.UL troff
126also provides a very general mechanism called `fields'
127for setting up complicated columns.
128(This is used by
129.UL tbl ).
130We will not go into it in this paper.