Thursday, 2 August 2018

Mystery Postmark and special offer.

A reader recently sent a scan of this postmark and asked if I knew what it is.

The text isn't too clear (click on the image to see it larger) but consists of the date 29-06-2018, the machine number ILSM: 2, and the time, 16:02:37Z.   I don't know what the 'Z' means in this case*.
The short answer is that it is a postmark applied by an Intelligent Letter Sorting Machine (iLSM) in test mode, which should not be applied to live mail, in this case a PPI mailpiece originating with UK Mail.
Update.  SP writes: "The Z in this context is probably “Zulu” time which is GMT."
I recall this from military usage.

Coincidentally shortly before this I had been offered some Royal Mail Engineering Test Cards, as shown below.  These are used internally in Royal Mail to verify that their machines are working properly prior to operational use. The destination is a test destination.  They can be used on iSLMs and IMPs (Integrated Mail Processors), with instructions on the reverse for how they are to be used.


I have a number of these available for regular readers/contributors who would like to add one to their collection.  Please email using the address at the top right of the page.   For international readers it would be best to include it with an order, but I will keep one reserved for you.  

Limited number only, when they are gone, they are gone.
Update: To those who have already asked, thank you for your emails.  I'm a bit busy lately with our club fair and fall out from that (ie acquisitions for my postal history collection!)

UPDATE: Still a few of these left if anybody would like one.


  1. Z following a date and time tends to denote UTC (Universal Coordinated Time and equivalent to GMT) It's a common convention in Computing but it is unusual to see outside scientific realms.

    1. It was widely used by the military before computers existed in every home and every business.

    2. Zulu was and is used by the military, but UTC only started on 1 January 1960.