The problem comes when the icon that it defaults to for printing is a right load, but the only way that envelopes can be loaded is in the center of the tray. I have an HP Colorlaserjet 3600 and an HP Officejet Pro 8600 and both load this way.
A technical definition of a function is: a relation from a set of inputs to a set of possible outputs where each input is related to exactly one output.
Function (mathematics) A function f takes an input x, and returns a single output f(x). One metaphor describes the function as a machine or black box that for each input returns a corresponding output.