What does the Standard/Summer version (X to Y °C) exactly mean?

Temperature - temperature of rock/concrete measured inside the hole,
X °C - approximate minimum application temperature, Dynacem version can be used below (works very slow) and above X (works faster),
Y °C - maximum temperature for safe application in hole diameters up to 42 mm,
Y+5 °C - maximum temperature for safe application in hole diameters up to 32 mm.
Each version is fast performing at the top of its application temperature range (breaks rock within 6-18 hours typically, at hole diameter of 40 mm) and may cause dangerous blow-outs above its maximum temperature for safe application Y.
Maximum temperature for safe application Y is only important (and can not be exceeded) in the moment of filling holes and during the first 4 hours after filling. For this reason, it is often possible to use Dynacem Standard in the summer if the cool holes are filled early in the morning.
Reaction slows down and breaking time increases almost 2 times with every 5 deg C drop in temperature, or with a hole diameter reduction to 30 mm.