747-200 Flap Ld Relief

[LAZYB]

Tell me how FLAP LD RELIEF works.

Flaps 30 you're good at 180 kts, but the LD RELIEF kicks back to Flap 25 if you're above 169 kts. ??? Does it care if you're accelerating or slowing? What's the "logic", and what's the "Q" switch?

Thanks