What is lemon powder? I am making a lemon cookies and it ask to roll it in lemon powder after baking?

I use a product , called "TRUE LEMON"...It is a powdered lemon juice available at supermarkets or online

I googled it and found several that were dried and ground lemon peel. Personally, I would make lemon sugar and roll them in that if it sounds like it would be good with the cookie recipe. It's just lemon peel whirred up with sugar.