Similarly, civil and religious adoption may not have happened at the same time (or even at all).In the case of Eastern Europe, for example, all of these assumptions would be incorrect.
Friday, 6 October 1867 was followed by Friday, 18 October.
Instead of 12 days, only 11 were skipped, and the day of the week was repeated on successive days, because at the same time the International Date Line was moved, from following Alaska's eastern border with Canada to following its new western border, now with Russia.
When this usage is encountered, the British adoption date is not necessarily intended.
The 'start of year' change and the calendar system change were not always adopted concurrently.
Thus "New Style" can either refer to the start of year adjustment, or to the adoption of the Gregorian calendar.