TYPO3: Set up German as the default language

To set German as the default language in TYPO3 (here: TYPO3 8.7.1), it is sufficient to assign the language parameters in the Template Setup. German is set as the default language and English as the second language. The Language ID and Language Codes are defined for each language:

 To do this, simply go to "WEB->Template" in the TYPO3 backend, select the desired template, and open the Template Setup for editing after selecting "Info/Modify". We then add the following:

#Default language
config.sys_language_uid=1
config.language=de
config.locale_all=de_DE
config.htmlTag_langKey=de

[globalVar = GP:L = 0]

# Configuration for &L=0
config.sys_language_uid=1
config.language=de
config.locale_all=de_DE
config.htmlTag_langKey=de

[global]

[globalVar = GP:L = 1]
# Configuration for &L=1
config.sys_language_uid=0
config.language=en
config.locale_all=en_EN
config.htmlTag_langKey=en
[global]

Next, prepare the parameter to be passed along:

config.linkVars:=addToList(L(0-1))

and define its uniqueness:

config.uniqueLinkVars=1

This completes the most important basic settings.