The enumerator that is used to mask NSEvent types. These correspond to user actions, like clicking, dragging hitting a key, using a scroll wheel, and even custom events that your application “makes up” (NSApplicationDefined).

NSEventType type = [NSEvent type];

See Apple’s docs at http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/ObjC_classic/Classes/NSEvent.html .

Values (taken from Apple’s AppKit Types and Constants page):

typedef enum _NSEventType { NSLeftMouseDown = 1, NSLeftMouseUp = 2, NSRightMouseDown = 3, NSRightMouseUp = 4, NSMouseMoved = 5, NSLeftMouseDragged = 6, NSRightMouseDragged = 7, NSMouseEntered = 8, NSMouseExited = 9, NSKeyDown = 10, NSKeyUp = 11, NSFlagsChanged = 12, NSAppKitDefined = 13, NSSystemDefined = 14, NSApplicationDefined = 15, NSPeriodic = 16, NSCursorUpdate = 17, NSScrollWheel = 22, NSOtherMouseDown = 25, NSOtherMouseUp = 26, NSOtherMouseDragged = 27 } NSEventType;