This article examines the basis of Natural Language Understanding of transformer based language models. such as BERT. It does this through a case study on idiom token classification. We use idiom token identification as a basis for our analysis because of the variety of information types that have previously been explored in the literature for this task. https://www.lightemupsequences.com/limited-deal-Women-s-ADU-RipStop-EMT-Pants-special-find/