That's it! There is nothing to add!
My source was the book "K.u.k. Seefligerchronik" by P.Schupita.
He told when the italians took over the navy station Pola, they didn't want to use any of the flying boats there, only to scrap them. But an US-guy asked to take some for evaluation. He choose this Hansa-Brandenburg W.13 and another one, which I don't know now. (The book is already back at the library

)
Of course full score to Marek, who was not misled by the markings and now is heading straight towards the top-10.
Scoreboard after challenge #594 -
Hansa-Brandenburg W.13 (UFAG built) - is:
108.80 Varese2002 ☼

76.70 Dave_Kent ☼
66.20 Rbailey ☼
33.30 Cruze☼
18.70 YavorD
18.15 Froggy
17.50 Aquilius
15.20 richard B
14.20 Flamingo
13.30 Rod Filan
11.90 Lodzermensch 
09.50 matte_kudasai
08.40 JohnMacG
08.10 Breguet
07.70 Dan-San
07.70 EdStevens
07.60 trp81
07.30 Patrick
07.10 Colin A. Owers
06.70 Ampovandak
06.10 joegertler
06.00 Eric Goedkoop
05.70 Doc
05.70 FOKKERJ Feuchtwanger
05.70 AROTH
05.60 ercoupepilot
05.45 GregE
05.30 Crimso
05.30 Der Grüne Flieger
05.20 Gilles
05.10 bshatzer
05.00 Tom L..........................have to wait 12 hours
04.70 dpolglaze........................ may start immediately
04.40 Ross Moorhouse
04.30 edmondthieffry
04.00 greenknight
03.70 Berman
03.70 Rufe
02.50 Gregoire
02.50 Rexee
02.10 Crankcase
02.00 austin08
02.00 Brad
02.00 Rickenbaron
02.00 sobrien
01.70 Kilian
01.60 sergio_vitalio
01.50 Albatros_Ace
01.30 Cigogne
01.20 Ransom E. Olds
01.00 airplane176
01.00 Catfish
01.00 Cliff
01.00 cubsfan4life
01.00 gregorydquist
01.00 Luf-Rick
01.00 Mike Westorp
01.00 paolomiana
01.00 Peter Zambori
01.00 rammjaeger
01.00 SL DIII
01.00 Tripehound
00.80 Machinbird
00.80 tbstreet
00.80 toxisch
00.60 Sreiko
00.50 ’14-‘18aviationcollector
00.50 Martin Irvine
00.40 Vilkata
00.30 albapfalzd30
00.30 Miroslav Pokorny
00.30 Nieuport14
00.20 Paul_J._Fisher
Marek, the next challenge is yours!
And enjoy your holiday!
(after almost 4 years in Austria I'm still not familiar with all those catholic holidays ...

)
Cheers
Aquilius