svn commit: r38993 - head/en_US.ISO8859-1/books/porters-handbook

[Eitan Adler]

Author: eadler (src,ports committer)
Date: Wed Jun  6 03:23:08 2012
New Revision: 38993
URL: http://svn.freebsd.org/changeset/doc/38993

Log:
  Add some explanation about how to allow
  "multi" options to permit zero selections
  
  PR:		docs/168675
  Submitted by:	crees
  Reviewed by:	Bryan Drewery <bryan at shatow.net>
  Approved by:	bcr

Modified:
  head/en_US.ISO8859-1/books/porters-handbook/book.sgml

Modified: head/en_US.ISO8859-1/books/porters-handbook/book.sgml
==============================================================================
--- head/en_US.ISO8859-1/books/porters-handbook/book.sgml	Wed Jun  6 02:06:20 2012	(r38992)
+++ head/en_US.ISO8859-1/books/porters-handbook/book.sgml	Wed Jun  6 03:23:08 2012	(r38993)
@@ -4286,6 +4286,21 @@ OPTIONS_SINGLE_SG1=	OPT3 OPT4</programli
 	  <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>