What is the `-0` flag in `tail`?

The Logstash documentation said about the input file plugin that it > Stream events from files, normally by tailing them in a manner similar to tail -0F but optionally reading them from the beginning. The tail man page said that -f, --follow[={name|descriptor}] output appended data as the file grows; an absent option argument means 'descriptor' -F same as --follow=name --retry But what is exactly the -0 flag in tail ?