some of you may find this interesting - especially if you are a non-pilot (like me) who enjoys ATC monitoring:
https://www.faa.gov/documentLibrary/media/Order/7110.65AA_Bsc_w_Chg_1_dtd_10_5_23.pdf
https://www.faa.gov/documentLibrary/media/Order/7110.65AA_Bsc_w_Chg_1_dtd_10_5_23.pdf