A plastic ring that must be in place on the hub of a magnetic tape reel before it can be written to or erased. Also write-enable?-ring; protection ring; file-protect ring.

• 一种塑料环，它必须在对磁带进行写入或擦除操作之前安装在磁带卷的中轴上。又称为允写环、保护环、文件保护环。