noun
call number
Library term for the classification code on a book's spine used to locate it on the shelf.
この本の請求記号は何ですか。
What is the call number for this book?
請求記号をもとに本棚から本を探した。
I looked for the book on the shelf using the call number.
書架記号 is a less common synonym for call number, also used in library contexts.
Compound of 請求 (request, claim) and 記号 (symbol, code), referring to the code used to request a specific item in a library.