The MMM and MMMM formats may include genitive names.

[geniuszxy]

Summary

According to this question: https://stackoverflow.com/questions/78446297/why-is-the-month-abbreviated-differently-when-the-date-format-includes-a-slot-fo, the MMM and MMMM formats may retrieve from the genitive names if there is a d or dd in the format string.

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Internal previews

📄 File	🔗 Preview link
docs/fundamentals/runtime-libraries/system-globalization-datetimeformatinfo.md	System.Globalization.DateTimeFormatInfo class
docs/standard/base-types/custom-date-and-time-format-strings.md	Custom date and time format strings

[geniuszxy]

@dotnet-policy-service agree

[BillWagner]

Ping @adegeo for review

[gewarren]

@tarekgh Could you review this?

[tarekgh]

The changes here look good to me. Can we add extra comment to the changes telling Genitive month names will be selected if the d or dd shows in the formatting date pattern? https://github.com/tarekgh/runtime/blob/202f26b3fa293187c35f530a56751e791ebb4ca9/src/libraries/System.Private.CoreLib/src/System/Globalization/DateTimeFormat.cs#L377

[geniuszxy]

@tarekgh, I made some minor changes to the description of MMM and MMMM in the custom date and time format strings to tell how genitive name is selected, please take a view.