I would define it as pitching for speed until preselected altitude in the altitude window on the MCP. This is regardless of thrust available. Because you can disconnect A/T, reduce thrust and the A/P will pitch to maintain speed until reaching the preselected altitude. At that point, it will pitch to maintain that altitude. I reckon if at some point thrust exceeds drag and weight (you advance the thrust levers yourself), it will eventually pitch up and at a later stage stabilize at an altitude that keeps the selected speed. Never tried it in the sim.
We use LVL CHG to driftdown to OEI MAX ALT at MAX CONT thrust.