O

object
  creation, abstracting
  registers to receive notice
objectForKey, 2^nd
Objective-C, 2^nd, 3^rd
onblur
onchange
onclick
oncontextmenu
ondblclick
onerror
onfocus
onkeydown
onkeypress
onkeyup
onload
onload attribute
onmousedown
onmouseenter
onmouseleave
onmousemove
onmouseout
onmouseover
onmouseup
onreset
onresize
onscroll, 2^nd
onselect
onsubmit
OOP (object-oriented programming)
OOP concept
  class
  framework
  inheritance
  message
  method
  object
  subclass
OpenAL, 2^nd
openDatabase
OpenGL
  EAGL
  standard template
OpenGL ES Application
Organizer
orientation
  and accelerometer
  interfaceOrientation
  notification
  of a view, checking
  precise, determining
  property
  UIDevice
orientation awareness, 2^nd
output
Overriding
  hitTest:withEvent: