HID Usage Tables Document 1.1 - C. Scott Ananian

78 Universal Serial Bus HID Usage TablesMultiple PointDigitizerFree Space WandCA – A 3D digitizer that detects the position of multiple points in space,typically through some non-mechanical means such as electromagneticsensors.CA – A 3D digitizer that detects the position of a point at the end of a handheldwand.15.2 Digitizer Transducer Collection UsagesStylusPuckFinger15.3 Digitizer Report Field UsagesCL – A stylus is a hand-held transducer that looks and is used like a pen. Adigitizer typically reports the coordinates of the tip of a stylus. The Styluscollection is a physical collection containing all the controls physicallylocated on the stylus. In the Stylus collection a Pointer physical collectionwill contain the axes reported by the stylus.CL – A puck, sometimes called a cursor, is a mouse-like transducer that restson a low friction surface. A digitizer typically reports the coordinates ofcrosshairs marked on the puck. The Puck collection is a logical collectioncontaining all the controls located on the puck. In the Puck collection aPointer physical collection will contain the axes reported by the puck.CL – Any human appendage used as a transducer, such as a finger touching atouch screen to set the location of the screen cursor. A digitizer typicallyreports the coordinates of center of the finger. In the Finger collection aPointer physical collection will contain the axes reported by the finger.Not all digitizer field usages are from the Digitizer usage page. In particular, the usages for X and Ydisplacement come from the Generic Desktop page.15.3.1 Digitizer-Specific FieldsTip PressureBarrel PressureIn RangeTouchUntouchTapQualityData ValidDV – Force exerted against the tablet surface by the transducer, typically astylus.DV – Force exerted directly by the user on a transducer sensor, such as apressure-sensitive button on the barrel of a stylus.MC – Indicates that a transducer is located within the region where digitizingis possible. In Range is a bit quantity.MC – A bit quantity for touch pads analogous to In Range that indicates that afinger is touching the pad. A system will typically map a Touch usage to aprimary button.OSC – Indicates the release of a finger from the surface of the touch screen.A system typically maps an Untouch usage to the release of a primary button.OSC – On a touch pad, indicates that the finger has been quickly lifted andreplaced on the tablet surface. This is typically mapped to a button event, butis distinct as no physical button is involved.DV – If set, indicates that the transducer is sensed to be in a relatively noisefreeregion of digitizing.MC – Indicates that the current data set is valid.Version 1.1 April 8, 1999