[TYPO3-dev] Where´s extTables.php in Typo3 7.4?

[Ernst Fall]

Good day!
I´m trying to add some fields into the backend to get some values into the rendered HTML-page.
Soä I found this https://docs.typo3.org/typo3cms/ExtbaseFluidBook/6-Persistence/2-configure-the-backends-inputforms.html documentation, which seems quite suitable. But I can´t find the extTables.php-file anymore. I just checked a Typo3 6.2-powered page and found it in typo3conf/extTables.php. With Typo3 7.4.0 I don´t see it :-(

Do you have any ideas where the file is located? Or is there a better approach in 7.4 to add fields to the backend?

Greetz,
Ernst