请看c.tld里关于out标签的定义：
<tag>
<description>
Like <%= ... >, but for expressions.
</description>
<name>out</name>
<tag-class>org.apache.taglibs.standard.tag.rt.core.OutTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<description>
Expression to be evaluated.
</description>
<name>value</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>
Default value if the resulting value is null.
</description>
<name>default</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>
Determines whether characters <,>,&,'," in the
resulting string should be converted to their
corresponding character entity codes. Default value is
true.
</description>
<name>escapeXml</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
=============================================================================
自定义标志的tld中的<attribute>结构中的rtexprvalue 属性是在运行时刻动态计算还是取编译进行时的静态值，如果为true，它就取得静态值，即：必须给它显现赋值，如：
<tag>
<name>codePopupTree</name>
<tag-class>com.neusoft.talentbase.framework.code.taglib.CodePopupTreeTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>type</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
此时在使用这个标签时必须像下面这个写：
<tb:codePopupTree type="CODE_AdministrationArea" />
rtexprvalue 属性的全称为
run time expression value
运行时表达式
Dear my visitors. Could you share your own understanding of the express"<rtexprvalue>true</rtexprvalue>"with me?I possible, could you give me some example?
What is more, I can't really seize the sentence below:
自定义标志的tld中的<attribute>结构中的rtexprvalue 属性是在运行时刻动态计算还是取编译进行时的静态值，如果为true，它就取得静态值，即：必须给它显现赋值，如