来源：
http://www.shydt.com/blog/article.php?type=blog&itemid=12
默认下列类型的文档是不缓存的。
Lists types of files that cannot be used offline. This policy lets you override the system's
default list of file types that are never cached for offline use.
By default, the system never caches files of the following types, as identified by their file
name extension:
File name extension File type
.slm Microsoft Source Library Management file
.mdb Microsoft Access database file
.ldb Microsoft Access security file
.mdw Microsoft Access Workgroup file
.mde Microsoft Access compiled module file
.pst Microsoft Outlook personal folder file
.db? Generic database file
通过更改组策略设置：
Computer Configuration Administrative Templates Network Offline Files 下的“Files not cached”可以手动设定特定类型的文件不被缓存，但是该设置会替代系统的默认设置，使用时，最好将上述系统默认不缓存的文件类型也一并添加进去。
