本规范通过定义可以使用WFSGetInfo、WFSAsyncGetInfo、WFSExecute和WFSAsyncExecute函数发出的特定于服务的命令，描述了XFS下供应商依赖模式（VDM）服务提供商提供的服务的功能。在所有设备类中，都需要某种方法进入特定于供应商的模式，以允许超出当前XFS规范范围的功能。这种模式的典型用法可能是处理某种配置或诊断类型的功能，或者对设备执行某种“离线”测试。这些功能通常在自助服务设备上以传统的维护模式或管理模式提供，通常需要操作员干预。当设备处于供应商依赖模式时，XFS服务提供商将提供那些未涵盖（且不要求涵盖）的供应商特定功能。此服务提供了切换到依赖于供应商模式的机制。VDM服务提供者可以看作是所有进入和退出VDM请求同步的中心点。

This specification describes the functionality of the services provided by the Vendor Dependent Mode (VDM) Service Provider under XFS, by defining the service-specific commands that can be issued, using the WFSGetInfo, WFSAsyncGetInfo, WFSExecute and WFSAsyncExecute functions. In all device classes there needs to be some method of going into a vendor specific mode to allow for capabilities which go beyond the scope of the current XFS specifications. A typical usage of such a mode might be to handle some configuration or diagnostic type of function or perhaps perform some 'off-line' testing of the device. These functions are normally available on Self-Service devices in a mode traditionally referred to as Maintenance Mode or Supervisor Mode and usually require operator intervention. It is those vendor-specific functions not covered by (and not required to be covered by) XFS Service Providers that will be available once the device is in Vendor Dependent Mode. This service provides the mechanism for switching to and from Vendor Dependent Mode. The VDM Service Provider can be seen as the central point through which all Enter and Exit VDM requests are synchronized.