Equivalent content: a brief lesson in basic design principles.
Equivalent content is content that serves the same function as that which it replaces. This equivalency is one of intent and meaning, not of visual appearance, unless the visual appearance is the meaning you are trying to convey. This is a critical and easily addressed point in making Web sites accessible.
Consider this good example of describing visual appearance:
This detail image of the hand of Michalengelo’s David clearly shows how it was disproportionately large, perhaps deliberately scaled to be more prominent when seen from a distance.