I just noticed that this patch has been classified under "bug fixes", but per Tom's comments, this is not a bug fix -- it seems we would need a new format code to implement some different week numbering mechanism. That seems a new feature, not a bug fix.
Therefore I propose to move this in Commitfest from "Bug fixes" to "Server features". This has implications such as not automatically moving to next commitfest if no update appears during this one. I've never personally had to write calendaring applications, so I don't have an opinion on whether this is useful. Why isn't it sufficient to rely on ISO week/day numbering (IW/ID), which appears to be more consistent? I think we should consider adding more codes only if real-world use cases exist for them. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services