该文件中含有Microsoft的数字签名信息
驱动程序必须将这个.cat文件包括进驱动程序的每一个分发介质中
Windows uses the presence or absence of a driver's digital signature to evaluate the quality of the drivers it attempts to install. Windows XP, Windows Server 2003, and Windows 2000 will warn users if they attempt to install drivers that don't have signatures. System administrators and individual computer owners can also choose to set operating-system policies that will prevent the installation of drivers that do not have digital signatures.