When using a non-synchronized manual transmission, what is the proper method to upshift?

Most heavy commercial vehicles use non-synchronized manual transmissions, which require the double-clutch technique to shift cleanly without grinding gears. To upshift: release the accelerator, push in the clutch and shift to neutral at the same time, release the clutch, let the engine and gears slow to the RPM required for the next gear, push the clutch in again and shift to the higher gear, then release the clutch and press the accelerator. Single-clutching a non-synchronized transmission causes wear on the gears and can damage the transmission. Skip-shifting is acceptable in some situations but is not the standard method for upshifting. The clutch is needed for every shift on a non-synchronized transmission, not only when stopping.