This style page summarizes Wikipedia "good practice" for Germany pages.
The choice of a style does not mean that other conventions are worse, or wrong. The sole purpose is to enable consistency among a large number of Wikipedia articles. Completed Wikipedia articles should mention the fact that other usages exist and in which contexts they are preferred.
Where applicable this style guide draws on the Country Compendium issued by the European Commission Directorate-General for Translation. European Commission Directorate-General for Translation (February 2017) [2011]. Country Compendium: A companion to the English Style Guide (pdf). European Commission. Austria. Retrieved 27 March 2017.
In general, for reasons of stylistic and regional consistency, the variety of English used in Germany articles is that which is recommended by the European Commission in its English Style Guide,European Commission Directorate-General for Translation (27 February 2017) [2011]. English Style Guide: A handbook for authors and translators in the European Commission (pdf) (8th ed.). European Commission. Retrieved 27 March 2017. i.e. the standard usage of Britain and Ireland, usually referred to as British English.
For conventions associated with Austrian articles see Wikipedia:WikiProject Austria/Conventions.