gentoo-overlay/dev-libs/boost/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>cpp</herd>
  <use>
    <flag name='tools'>
      Build and install the boost tools (bcp, quickbook, inspect,
      wave)
    </flag>
    <flag name='eselect' restrict='&lt;dev-libs/boost-1.50.0-r2'>
      Run "eselect boost update" even if version is already selected
    </flag>
    <flag name='debug'>
      Build and install debug versions of the Boost libraries. These
      libraries are not used by default, and should not be used unless
      you're developing against Boost.
    </flag>
    <flag name='threads'>
      Build multi-thread-compatible libraries instead of
      single-threaded only.
    </flag>
  </use>
</pkgmetadata>