Sure! Let's break down the term "call mark."
Call mark (noun): A call mark is a special set of letters or numbers written on a book or other materials. It helps librarians and readers find the book's location on the shelves in a library.
In larger libraries, call marks can be more complex and may include various letters and numbers that represent different subjects or categories.
There aren't specific idioms or phrasal verbs directly related to "call mark." However, you might hear phrases like "looking for a book by its call number," which means searching for a book using its designated mark.
A call mark is important for organizing and finding books in libraries. It is a straightforward system that helps everyone locate books efficiently.