When you open the PDF, the layout can be dense. Here is a quick cheat sheet on reading the rows:
: A standardized list of unique alphanumeric codes assigned to aerodromes and aeronautical fixed stations. doc 7910 pdf
Controllers use these codes to identify handoff points between different FIRs (Flight Information Regions). For example, handing off a flight from Vancouver (CYVR) to Seattle (KSEA) requires absolute certainty of the codes. When you open the PDF, the layout can be dense