A very interesting read, thanks for posting the link.
A customer sent me the following link which is a PDF of the January 2004 article on the IWC and JLC Mk XI navigational wristwatches.
http://www.gregsteer.net/IWC/Mark_11/mark11a-en.pdf
Eddie
Whole chunks of my life come under the heading "it seemed like a good idea at the time".
A very interesting read, thanks for posting the link.
F.T.F.A.
The Mark 11 paper also appears in Konrad Knirim's mighty tome 'British Military Timepieces'. It starts on page 672.
If you didn't already know or haven't got to pages 705 and 706 yet, these two pages refer to, or picture the Precista PRS 17 and PRS 18.