On 10/23/2015 01:52 PM, Even Scharning wrote:
All credible sources I have found, say that CET is a constant UTC+1.
Many sources also use "Central European Time" to denote either UTC+1 or UTC+2, depending on whether daylight saving time is in use. For example, "Most of the cities in this book are on Central European Time, which is 1hr. ahead of Greenwich Mean Time (GMT) and observes Daylight Saving Time during the summer." -- Let's Go Europe 2012. North American practice is to use phrases like "Pacific Time" when one wants the time zone independently of whether DST is in use, and phrases like "Pacific Standard Time" and "Pacific Daylight Time" when one wants to specify whether DST is in use. There's no similar convention for European time zones, so phrases like "Central European Time" are ambiguous in practice, and careful writers should specify which meaning is intended -- as is done in the abovementioned quote from "Let's Go Europe".