The Rules of Engagement: Marls

I should be re-admitted if I exhibited all those marls of benign normality - holidays, dinner parties - that are the province of the maintained and protected...

The Rules of Engagement, ch. 8

I've checked that sentence in both the printed first edition and the electronic version. Both show 'marls'. Surely 'marks' is meant? You don't really expect compositorial errors in a modern book, but it isn't the only example in Brookner. See an earlier post here.