asp.net <％$...％>语法

ConnectionString="<%$ ConnectionStrings:sqlconnection %>"

这是一篇很好的文章，解释了所有的内联表达式：
http://support.microsoft.com/kb/976112

The expression builder is used to set values of control properties based on the information that is contained in an application’s configuration or resource files. The following is the basic syntax of the expression builder:
<%$ Expression Prefix: Expression Value %>
The dollar sign ($) indicates to ASP.NET that the following expression is an expression builder. The expression prefix defines the kind of expression,such as AppSettings,ConnectionStrings,or Resources. Additionally,you can create and define your own expression builder. The expression value that follows the colon (:) is what ASP.NET will actually use as the value of a certain property.