> The RFC for UUID type 4 says the digit "4" must be set on the 14th byte. The loop checks to see if this is the case, and loops if it is. The RFC for UUID typ

> The RFC for UUID type 4 says the digit "4" must be set on the 14th byte. The loop checks to see if this is the case, and loops if it is. The RFC for UUID type 4 states that bits 48 through 51 (0-based indexing) are set to 4, resulting in the character at position 14 (0-based indexing) of the hyphenated string representation being '4'. Also, this post does a little more than that. It also notes that the version 4 UUIDs we use in software today are variant 10₂ UUIDs. This is quite unsurprising too because the other variants are reserved. There is a second infinite loop in the post that demonstrates this by testing the two bits that represent the variant number. > why is that worth blogging about? Hello! I am the author of this post. This is my weblog, so I log about things that I find interesting here. In this case, the interesting thing for me was not so much that we can make an infinite loop out of a triviality but the triviality itself, i.e., not all bits of variant 10₂ of version 4 UUIDs are random, and then finding the sections in the RFC that define these bits. The infinite loops only serve as demos that there are definitely six bits that are not random. Indeed the infinite loop is just testing whether a version 4 variant 10₂ UUID is a version 4 variant 10₂ UUID and that is bound to be an infinite loop. However, I also wanted to document on my weblog where exactly the version and variant bits are located along with references to the relevant sections of the RFC. That is slightly less trivial than documenting that 1 is 1. I understand this is not going to be interesting to everyone. But this is my weblog, so I don't have to subscribe to others' notion of what is interesting to decide what I must add to my own weblog. I believe a more meaningful question would be whether this post is worthy of HN or not. Well, the moderators and the community determine that by voting with their fingers. In this case, it looks like this post is indeed not too interesting for HN, so I would have agreed with you if that were your point.