Use these reviewed values to observe exact field boundaries. The examples explain what a local structural check can establish and, equally importantly, what it cannot establish about a record or caller.
UUIDv4 vector
The value 919108f7-52d1-4320-9bac-f847db4148a8 has 4 as the first digit of its third group, so its version is four. The fourth group starts with 9, whose leading binary bits are 10, the RFC variant. The remaining data is random in the referenced example. UUIDLens reports sixteen bytes and does not claim where a copied vector originated.
UUIDv7 vector
The value 017f22e2-79b0-7cc3-98c4-dc0c0c07398f begins with the hexadecimal timestamp 017f22e279b0. Converting that unsigned 48-bit field gives 1645557742000 milliseconds, or 2022-02-22T19:22:22.000Z. The version digit is 7 and the fourth group begins with 9, so the RFC variant is present. Later fields remain data, not a signature.
Reproduce the check
Open the validator preset, paste the vector exactly and compare the canonical text, version, variant and hexadecimal bytes. Adding a space, changing a letter to uppercase or wrapping the same bits in braces intentionally fails this strict contract. That failure does not say another parser could never accept the representation; it says the tested canonical-input contract was not met.