Other issues to watch out for when food, wax, etc. is attached to the part where there is no letters, numbers, etc.
Removing Contact Lenses from a Solution Which May Contain a Strainer;
Foods - Putting Cocoa Powder with Milk, Making Soda, Making Seltzer, Ice, and Cases Where It Does Apply to Food;
(Temporary Ohel) Very important ins and outs in conjunction with a covering on a Sukkah;