First thing is that's not a NOTAM it's something that has been derived from a NOTAM.
However it's a good illustration of the perils of doing things that people think are legitimate and "official" but which have pitfalls.
The FIR concerned is EHAA. If you go to the
US Defense Internet NOTAM Service and look at the NOTAM for EHAA you won't find that NOTAM, which suggests that DINS is not a good place to go for your NOTAM if you are flying in Europe!
If you go to the UK AIS site you get it and it is presented like this
Q) EHAA/QRACA/IV/NBO/AW/000/999/5255N00454E137
B) FROM: 10/08/19 04:15C) TO: 10/08/23 19:02
E) SPECIAL RULES ZONES ESTABLISHED DURING SAIL 2010.
FOR ADDITIONAL INFO SEE
Homepage - OPS help desk LVNL.
LOWER: GND
UPPER: UNL
SCHEDULE: SR-SS
A1037/10
Which, while still not the complete raw NOTAM text does at least contain the Q Line
Decode reads
EHAA - The FIR
QRACA - Airspace Reservation Activated
IV - affects IFR & VFR
NBO - For immdiate attn of a/c operators, for inclusion in Preflight Info Bulletins (PIB) and concerns flight ops
AW - Aerodrome NOTAM and NAV Warning
000/999 Range of FL affected (surface to unlimited)
5255N00454E - geographic centre of the activity
137 - radius in nm of a circle based on that centre that would enclose the activity
The plain text includes SCHEDULE: SR-SS, which are ICAO abbreviations and can be found in GEN2.2 of any AIP. Meaning is Sunrise-Sunset.
The fact that the explanatory stuff is in Dutch and not English is something to take up with Netherlands AIS. If however you look at the chart that is on the site, even though it is in Dutch it will show that the affected area is a dumbell shaped area with a max height of 3000ft. At a guess the reason why the NOTAM height is to FL999 is because SAIL 2010 involves tall ships with high masts that will constitute obstructions within the ATZ and Eurocontrol's OPADD (Operating Procedures for AIS Dynamic Data) require obstacles within an ATZ to be notified to that height.
At the end of the day if you want to have a bitch about a NOTAM you need to go first to the AIS of the State of issue, who should be able to tell you who was the originator so you can in turn go and have a whinge at him.