uuid

Create a string representation of this UUID
using lowercase letters

e.g. f81d4fae-7dec-11d0-a765-00a0c91e6bf6

The value of this UUID as an u128

For an UUID of variant 8 to B (the ones specified in RFC9562) all bits
without the bits of version and variant field, for an version 4 UUID
these are the random bits, for version 8 the custom data

returns an u128 with 122 bits of data

the 4 bits of the variant field as a decimal number

always returns all 4 bits, which can include don't care bits

https://datatracker.ietf.org/doc/html/rfc9562#name-variant-field

the version field as a decimal number

https://datatracker.ietf.org/doc/html/rfc9562#name-version-field

Version 8 UUID containing 122 bits of custom data

https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-8

Version 4 UUID containing 122 bits of random data

https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-4

Create a UUID from its String representation

Does not check for valid version, variant, etc.

Hexadecimal digits in groups of 8-4-4-4-12
XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
where X is a hexadecimal digit

Create a UUID from an u128

Does not check for valid version, variant, etc.

does a come before b or is equal to b?

The Max UUID is a special form of UUID that is specified to have all 128 bits set to 1

This UUID can be thought of as the inverse of the Nil UUID
A Max UUID value can be used as a sentinel value in situations where a 128-bit UUID
is required, but a concept such as "end of UUID list" needs to be expressed and is
reserved for such use as needed for implementation-specific situations.

https://datatracker.ietf.org/doc/html/rfc9562#name-max-uuid

The Nil UUID is special form of UUID that is specified to have all 128 bits set to zero

A Nil UUID value can be useful to communicate the absence of any other UUID value in
situations that otherwise require or use a 128-bit UUID. A Nil UUID can express the concept
"no such value here".
Thus, it is reserved for such use as needed for implementation-specific situations.

https://datatracker.ietf.org/doc/html/rfc9562#name-nil-uuid