it is best to be safe and contact the shop or the teacher. the term shirting can be misinterpreted. To me it is not a term that is generaly used and identification known. If I went out and look for it I would relate it to the shirt fabric made and worn in the early 1890's - a reproduction type fabric. So everyone may have a different take on what the word means. It is better to describe the pattern and color. This is what causes confusion with students.