"Il écrit une lettre longue" should be valid?
"longue lettre" because it's a Size and one must follow the BAGS rule (Beauty, Age, Good and bad, Size)
What exactly is the BAGS rule?
I thought it was BANGS. Beauty, Age, Number, Good/bad, Size?
I believe you are correct. I'm on mobile so I can't click the article, but if it is the same about.com article I read on the rule it outlines it as the BAGS rule. But "number" definitely applies, too.
Follow my link up there ^
Beauty, Age, Good and bad, Size.
Thank you! That's very helpful.