Contest 7: Which service stamps are these?
Between 1921 and 1923, proofs were made for service stamps by overprinting existing postage stamps. At that time, the Dutch State comprised a number of Departments. Separate service stamps were produced for each of these departments, bearing an abbreviation of the relevant department. However, the service stamps were never issued! What did the abbreviations on the accompanying stamps mean?
DEP. v. A.
DEP. v. BNL.
DEP. v. BTL.
DEP. v. F.
DEP. v. J.
DEP. v. K.
DEP. v. L.N.H.
DEP. v. M.
DEP. v. O.
DEP. v. O.K.W.
DEP. v. W.
Thanks to Cees Janssen for this puzzle. 
The abbreviations stand for Department of, in order:
Labour/ Interior/ Foreign Affairs/ Finance/ Justice/ Colonies/ Agriculture, Industry and Trade/ Navy/ War/ Education, Arts and Sciences/ Water Management.
I can certainly agree with Toon's list. These were the ministries of the Ruijs de Beerenbrouck I Cabinet (1918-1922)
@Toon, sorry for my late reply, but it's perfectly fine! Congratulations on the answer to this final contest.
'@Lia,
I suspect you enjoyed some oliebollen. That should be allowed on January 1st. I enjoyed delicious fish and a nice white wine.
When will the winners be contacted? By the way, I really enjoyed the contests 🙂
It is interesting to know that separate service stamps were eventually introduced for a number of departments: Foreign Affairs, Justice, Colonies, Public Works and Water Management, (Chancellery of Law, Consular Service, ...). Designed by Mr. de Rooi and printed by Joh. Enschede & Zonen in Haarlem. Although a number of Departments were already Ministries in name, the Department stamp was still used in the beginning. I collect these fiscal stamps and am curious whether the other Departments also introduced these stamps.