When you're dealing with massive exports or imports, that's when you deal more with compiled MARC. For instance, many libraries share their info with OCLC through these exports, and this is one way to do it.

A real cataloguer would be better able to explain this, but if you're using WorldCat as a cataloguer, you're likely interacting with it using a protocol called Z39.50. OCLC will respond with its own record which contains the basic MARC that you can use to add to your system and edit as needed.

Cataloguers can and should correct me on this, but most of the times, compiled MARC is used for imports and exports and transportation. So one could have a single record in the file or thousands.

Often the MARC records themselves come from various library data vendors like OCLC.

It was one of the company’s biggest selling points at launch. MARC still receives updates and new tags and all that, so it had to be databased in a way that facilitated those updates. It takes a bit to learn the ins and outs of all the tables used but once you get it, it makes sense.

Mostly. 😅

Some integrated library systems will hold MARC records in a sort of separate way, to be called on as needed. Polaris ILS, which is what I use, is the only ILS that I know of that managed to put MARC into a database format. Polaris can build MARC records from tables in the database.

@everettruessfans.bsky.social Oh yeah, MARC is absolutely still used in most modern libraries. The formatting can vary, but the standard remains. There are compiled MARC files, but you'll find it in XML and JSON too.

The real variety comes down to how it's stored in a library system.