1@Section
2   @Title { Multiple columns }
3   @Tag { columns }
4@Begin
5@PP
6You can change the number of columns of text per page, and the width of
7columns. @Index columns
8multiple.columns @Index { multiple columns }
9the gap between the columns, by changing these two setup file options:
10columnnumber. @Index @Code "@ColumnNumber"
11columngap. @Index @Code "@ColumnGap"
12@ID @OneRow @Code {
13"@ColumnNumber { 1 }"
14"@ColumnGap { 1.00c }"
15}
16If you are using your own setup file (Section {@NumberOf setup}), you can
17find and change them there.  If not, @Code "@ColumnNumber" may be changed
18at the beginning of your document (Section {@NumberOf ordinary}).
19@PP
20@Code "@ColumnNumber" may be any number between 1 and 10, with default
21value 1 as shown, and @Code "@ColumnGap" may be any length (Section
22{@NumberOf objects}).  The column width is derived from these options
23column.width @RawIndex { column width }
24column.width.in.pages @SubIndex { in pages }
25using the obvious formula
26@ID @Math { columnwidth = { pagewidth - margins -
27({@Code "@ColumnNumber"} - 1) times {@Code "@ColumnGap"} }
28over @Code "@ColumnNumber"
29}
30You must ensure that this comes to something reasonable.
31@PP
32These two options do not apply to pages containing an index.  For them
33there are similar setup file options called @Code "@IndexColumnNumber"
34and @Code "@IndexColumnGap" (Section {@NumberOf indexes}).
35@PP
36Most document types permit you to have multiple columns, but certain
37things will be kept full width regardless of the @Code "@ColumnNumber"
38option:  figures and tables, chapter headings, and so on.  The details
39vary with the document type, so are deferred to Chapter {@NumberOf types}.
40@End @Section
41