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Add some explanation about how to allow

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"multi" options to permit zero selections

PR:		docs/168675
Submitted by:	crees
Reviewed by:	Bryan Drewery <bryan@shatow.net>
Approved by:	bcr
This commit is contained in:
Eitan Adler 2012-06-06 03:23:08 +00:00
parent 0853bbe16a
commit ecb02b697f
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=38993
1 changed files with 15 additions and 0 deletions

15
en_US.ISO8859-1/books/porters-handbook/book.sgml
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@ -4286,6 +4286,21 @@ OPTIONS_SINGLE_SG1= OPT3 OPT4</programlisting>
<programlisting>OPTIONS_MULTI= MG1
OPTIONS_MULTI_MG1= OPT5 OPT6</programlisting>
<para><makevar>OPTIONS_MULTI</makevar> and
<makevar>OPTIONS_SINGLE</makevar> can also allow zero
choices by including the group in
<makevar>OPTIONS_DEFINE</makevar>:</para>
<programlisting>OPTIONS_DEFINE= MG1
OPTIONS_MULTI= MG1
OPTIONS_MULTI_MG1= OPT5 OPT6</programlisting>
<para>This group then requires at least one
<makevar>OPTION</makevar> from <makevar>MG1</makevar>
only if the new <makevar>MG1</makevar>
<makevar>OPTION</makevar> is selected. Experimentation
is encouraged to ensure that this is understood.</para>
<para><makevar>OPTIONS</makevar> are unset by default,
unless they are listed in
<makevar>OPTIONS_DEFAULT</makevar>:</para>