[xml基础]ENTITY的用法

荒野狐狸

为什么我这段总也通不过？

<?xml version="1.0" encoding="gb2312"?>

<!DOCTYPE IMAGE [
<!ELEMENT IMAGE EMPTY>
<!ATTLIST IMAGE SOURCE ENTITY #REQUIRED>
<!ENTITY Logo SYSTEM "Logo.gif">
]>

<IMAGE SOURCE="&Logo;"/>

总是提示我"General entity referece '&Logo;' is not allowed in attributes of type ENTITY or ENTITIES"

我也试过<IMAGE SOURCE="Logo"/>
也不行，提示"In attribute 'SOURCE' name 'Logo' must not refer to a parsed entity.

大家帮我看看啊，谢谢