While most countries have a consistent week numbering method, sometimes it's needed to adjust the settings to something different. The defaults in DigiCal are based on the country you've selected in the system's Language & Input screen. Please note that means that if you have selected English (US), this will also set all the date and time settings to the US version; in Europe, you can select English (UK) instead if you don't want to use the US week number variants.
The common week numbering systems are:
US, Canada & Mexico
Weeks start on Sunday in the USA, and the first week of the year is the week with 1st of January. This means that the first/last week of a year is assigned both week number 1 and 52/53.
ISO Week numbers
In Europe, the first day of the week is Monday, and the first week of the year is the week with the first Thursday. 1st of January can be in week number 52 or 53, but there are no weeks with two week numbers like in the USA system.
In the middle east, most countries use the same system as in the US, but the weeks start with Saturday.
How to configure this in DigiCal
Please go to DigiCal > menu > preferences > date & time
As said before, the default settings uses the country from the system settings, but if you need to adjust it because you need to see ISO week numbers, you can do so in DigiCal.
Change the First day of the week and Days in first week setting according to the next table:
*For example, if you want to keep your system default on the United States but want Monday as the first week, you'll need to change the First day of the week to Monday and Days in first week to 4 in DigiCal's settings menu. This will prevent issues with the wrong week number.