ISO Defines the Week Number Standard
ISO 8601 defines an international standard for calendar and time formats. One of its provisions includes the "ISO week date," where Monday is considered the start of the week, and W01 is defined as the week containing the first Thursday of the year. For example, December 30, 2024, to January 5, 2025, corresponds to 2025-W01.
The Japanese Industrial Standards (JIS) also adopt a Monday start for weeks, in line with ISO. However, the Japanese Labor Standards Act considers Sunday as the start of the week.
You can obtain the week number using the following Linux command:
date +%V
Looking back at my Obsidian logs, I realized I had researched the same topic around this time last year.