0.9,de-de

: Developers use these strings to test how their applications handle internationalization (i18n) and localization (l10n).

The value de-DE;q=0.9 tells a website that is your preferred language, with a "quality value" (q) of 0.9. This value ranges from 0 to 1, where higher numbers indicate a stronger preference. How to use this feature 0.9,de-DE

The request refers to setting a language preference within a browser's Accept-Language header. : Developers use these strings to test how

: For older versions of Edge or Internet Explorer, users have modified the AcceptLanguage key under HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International to force these specific quality values. 0.9,de-DE