The Shape of Code

As a member of IST/5, the British Standards’ programming language committee, I receive a daily notification of relevant documents that have arrived at BSI. The email arrives just before midnight and contains a generous helping of acronyms, such as: N13344 SC 28 ISO-IECJTC1-SC28 N2051 NWIP for Monochrome inkjet yield.

The line break on the above line resulted in “Monochrome inkjet yield” appearing at the start of a line and it caught my attention, so I downloaded the document.

SC28 is the ISO committee for office equipment and this NWIP (New Work Item Proposal) is for WG2 (the Working Group responsible for consumables) to create a new ISO Standard with the title: “Method for the Determination of Ink Cartridge Yield for Monochrome Inkjet Printers and Multifunction Devices that Contain Printer Components”. Voting, on whether or not work should start on this proposal, closes on July 12.

Why was information about inkjet yield sent to a programming language list? Are SC28/WG2 having a membership drive and have been tipped off that our workload is declining? More importantly, are they following the C++ model of having regular meetings in Hawaii; the paperwork does not say. The standard for color injet printers appeared in 2009; was the production of this document such a traumatic event that it decimated committee membership and it has taken eight years to put together a skeleton group.

Attached to the proposal is a 20-page draft document; somebody has been busy.

So how is it proposed that monochrome inkjet yield be calculated? You need at least nine inkjet cartridges, three printers and a room at a temperature of 23 degrees (plus/minus 2 degrees, with readings taken every 15 minutes and an hourly running average calculated; “… temperature can have a profound effect on test results.”). Load “… a common medium weight paper and must conform to the printer’s list of approved papers.” into the three printers that have been “… temperature acclimated to the test room environment.” and count the number of pages printed by each printer (using at least three cartridges in each printer) before “…an end of life judgement.” Divide total number of pages printed by total number of cartridges used and there you go.

End of life? “The cartridge yield is determined by an end of life judgement, or signalled with either of two phenomena: fade, caused by depletion of ink in the cartridge or automatic printing stop caused by an Ink Out detection function.”

What is fade?
“3.1 Fade
A phenomenon where a significant reduction in uniformity occurs due to ink depletion.
NOTE In this test, fade is defined as a noticeably lighter, 3 mm or greater, gap located in the text, in the bar chart, or in the boxes around the periphery of the test page. The determination of the change in lightness is to be made referenced to the 25th page printed for each cartridge in testing. For examples of fade, please consult Annex A.”

And Annex A?
“Examples of Fade <future edit: add picture>”

Formula for calculating the standard deviation and a 90% confidence interval are given (the 90% confidence interval formula assumes a Normal distribution; I would have thought that the distribution of pages printed by a cartridge might be skewed and a bootstrap procedure would be more reliable).

It is daylight now and my interest in inkjet yield is satiated. But if you, dear reader, have a longing for more, then Ms. Michelle Pangborn (Hewlett-Packard), USA or Mr. Nobuaki Hamada (Epson), Japan are the people to contact.

Some printer test pages to add to your link collection.