> For the complete documentation index, see [llms.txt](https://docs.helmut.de/helmut4-releases/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.helmut.de/helmut4-releases/v4.7.0/helmut4-components/helmutio/streams/io-event-triggers/prestream.md).

# PRESTREAM

The prestream will be executed when a certain profile with existing prestream is triggered. Before operating the main stream, the prestream will be operated beforehands.