Safety cover
Also called: pool safety cover, ASTM F1346 cover, anchored safety cover.
A safety cover is an in-ground pool cover, mesh or solid, that anchors into the deck and is certified to ASTM F1346, the standard for holding a person's or a pet's weight without letting them into the water. A winter debris cover that simply lies on the water is not one.
Why it matters
A cover is a safety cover only if it says so, whatever a listing claims about heavy duty. GLI, for one, states its HyPerLite meets or exceeds ASTM F1346-91. There is no above-ground version: every above-ground winter cover, mesh or solid, is a debris cover that does not hold a person or a pet, so a closed above-ground pool still needs its own barrier through the winter. When closing, read the cover manual before lowering the water, because safety covers specify a maximum water depth from the cover. At the premium tier, ask how much light the fabric blocks and how it sheds water.
In numbers
With a mesh safety cover, keeping the water within 18 inches of the top of the pool matters a lot for reducing stress on the cover, per Meyco's guidance.