The capability of a collection is defined by its usage, reports, link collections, and controls. To obtain a summary of a collection's capability, a user-mode application or kernel-mode driver calls HidP_GetCaps to obtain a HIDP_CAPS structure. This structure contains the following information about a collection's link collections, button capability arrays, and value capability arrays:
The size, in bytes, of the collection's input, output, and feature reports (see Introduction to HID Concepts)
For each report type, the number of buttons and values supported by the collection, as specified by the NumberXxxDataIndices member.