Maggie/All Chasers

[Madam Xiomara Hooch]

Maggie, you can't mark August while he's the Keeper. The rules in Quidditch Important Notices specifically refer to Chasers. I'm prepared to consider making it possible to mark Beaters and possibly other positions, but since we're some way into this game now, we'll have to keep the rules as they are - you may only mark Chasers.

I suspect that marking Keepers wouldn't be allowed anyway, judging from Muggle games...