What a lot actually is
A lot is one production run of one material, filled and sealed as a unit. Every analytical result, every certificate and every retained sample refers to that run and to nothing else. A second run of the same compound is a different lot, and it needs its own testing.
This is why a supplier can hold a genuine certificate and still be unable to tell you anything about the vial you received. If the vial carries no lot, or the lot is a description of the cap rather than a batch identifier, the paperwork and the material cannot be connected.
The failure mode to watch for
The common pattern is a single impressive figure quoted across an entire catalogue. It reads as a specification, but a specification is a target the material is tested against, not a measurement of the material itself.
A result reads differently. It names a compound, a lot, a date, a method and a laboratory. If any of those is missing you cannot reproduce the check, and neither can anyone else.
What we publish, and what we do not
Where a laboratory printed a measured figure for a lot we hold, that figure appears on the product page next to the lot it came from, and the certificate is linked.
Where a certificate confirms the material met its specification without printing a figure, the page says so instead of inventing a percentage. Where no certificate exists for a lot, the page says pending. Those three states are different claims and we keep them different.