Auto naming logic for ID graphic objects

Question

Can anyone tell me what logic is used for the naming of JPG/PNG images that are generated for InDesign-drawn boxes, line, ovals, groups, etc?
In other words, if you draw a circle in InDesign, anchor this to the text, output as reflowable EPUB, unzip the EPUB, and look in the oebps\image folder, you'll see an image named something like 2022.jpg. I'm trying to determine the logic behind this naming, as I need to reuse these images for something else.

Answer 1

Thank you Douglas. This is really helpful.
Here is what I need this for: I've got a large scripting project where a health care client has 2500+ ID files that are very regular in their layout, structure, use of styles, etc. They need to get the content from these documents, along with the simple layout (h1, h2, h3, body, etc) into various CMS. Some of the CMS ingest HTML, some XML, etc. I've written a series of scripts that help a user quickly check/cleanup/"normalize" a document, and then export to html/xml per the specifications of the CMS.
For various reasons, I'm using InDesign's HTML export engine as the starting point, so it creates a "web-resources" folder and dumps the images in there. We need to dump the images that are generated from each document's export into a common images folder. We can be guaranteed that the placed image filenames are unique. But it looks like the auto-generated filenames from the UID will not likely always be unique, so I'll probably add a timecode or something to the filename to ensure that it is unique.
This is a very unique and challenging project. I'm having fun with it.