The variables begin_month, begin_week, and begin_day define the month, week, and day, respectively, when DST begins. The variables end_month, end_week, and end_day define when DST ends. Months are 1 (January) through 12 (December); weeks are 1 through 4; days are 1 (Sunday) through 7 (Saturday).
You can use negative numbers to specify the weeks, where -1 is the last week of the month, -2 is the second to last week, and so on. For example:
DSTlaw=4, 1, 1, 10, -1, 1
Defines DST as beginning in April (4), on the first week (1), on Sunday (1); and ending in October (10), on the last week (-1), on Sunday (1).
For Europe this setting needs to be
DSTlaw=3, -1, 1, 10, -1, 1