The <#2690#><TT>root</TT><#2690#> class is a subclass of the basic <#2691#><TT>composite</TT><#2691#> class,
but <#2692#><TT>root</TT><#2692#>s are different from ordinary composites in several ways.
<A ID="2693"><tex2html_anchor_invisible_mark></A>
<UL>
<LI>The parent of a <#2695#><TT>root</TT><#2695#> is <#2696#><TT>nil</TT><#2696#>.
</LI>
<LI>The geometrical attributes of a <#2697#><TT>root</TT><#2697#> cannot be changed.
</LI>
<LI>A <#2698#><TT>root</TT><#2698#> is always created automatically when its
<#2699#><TT>contact-display</TT><#2699#> is created. A <#2700#><TT>root</TT><#2700#> is never created by an
application.
</LI>
<LI>The <#2701#><TT>name</TT><#2701#> of a <#2702#><TT>root</TT><#2702#> is
initialized automatically when it is created. The initial resource name is <#2703#><TT>:SCREEN-</TT><#2703#><#2704#><EM>n</EM><#2704#>, where <#2705#><EM>n</EM><#2705#> is the index of the
<#2706#><TT>xlib:screen</TT><#2706#> object in <#2707#><TT>(xlib:display-roots
contact-display)</TT><#2707#>~<A NAME="footfnm3"
HREF="#fnm3" TARGET="footer"><SUP>50.3</SUP></A>.
</LI>
<LI>A <#2709#><TT>root</TT><#2709#> composite imposes no geometry management policy.