RequestType is bit-mapped and identifies the type of Descriptor request and the recipient. The type of request may be 'standard', ...

RequestType is bit-mapped and identifies the type of Descriptor request and the recipient. The type of request may be 'standard', 'class' or 'vendor-specific'. The recipient may be 'device', 'interface', 'endpoint' or 'other'. Refer to the USB Specification for the appropriate values for each bit.