A verification mark is the nine-character code a verifier applies to a measuring instrument once it passes verification for trade. It combines the servicing licensee’s three-letter mark, the verifier’s four-digit code and a code for the month and year, such as ABC0234K2, under National Measurement Institute (NMI) rules.
OpsChase for trade measurement verifiers builds the mark for each job.
How to read a mark
- ABC: the servicing licensee mark, three uppercase letters.
- 0234: the verifier code, the last four digits of the verifier’s registration number, VR-00234.
- K2: the month and year of verification. Months run from A for January to L for December, and the year is its last digit, so K2 is November 2022.
Where it goes
NMI says the mark can go on a label fixed to the instrument, a stamp plug or the instrument’s surface, somewhere easy to reach, unlikely to be damaged and, if possible, visible to customers. Each instrument carries one mark, and it must be permanent. NMI supplies adhesive verification labels free to servicing licensees on request.
Marks are not seals
Seals must be tamper evident and carry only the three-letter servicing licensee mark. NMI’s verification labels must not be used as seals. Advertising stickers must not be confused with a mark; NMI suggests adding “this is not a verification mark”.
On the form
On Form 6 and Form 6A, the verifier’s mark field takes seven characters, such as ABC0234, with no month and year code. When an instrument is re-verified, the previous mark is removed or obliterated. Read the full guide to verification marks.
How OpsChase handles marks
OpsChase builds each mark from the licensee mark, the verifier’s code and the test date’s month-and-year code, records pass, fail or non-verification with a reason, and uses the seven-character version in the form export. Every mark is kept against the instrument. OpsChase is independent software and is not made or endorsed by NMI.
On OpsChase: one queue for your team and contractors, follow-up when a job goes quiet, and photos or sign-off before it closes. Book a demo — one site or many.
- What does J6 mean on a verification mark?
- October 2026. J is the month code for October and 6 is the year code for 2026.
- Can one instrument carry two verification marks?
- NMI says to mark an instrument with one verification mark, and to remove or obliterate the previous mark when it is re-verified.
- Who supplies verification labels?
- NMI supplies adhesive verification labels free to servicing licensees, on request from the licensee’s nominated contact person.