What is the meaning of %F, %T, and %s in fetchmail's mda option?

Browsing through web pages around the World Wide Web, I often come across ~/.fetchmailrc examples such as:

poll mail.example.com
    port 993
    proto imap
    user "max123" password "123456"
    mda "/usr/bin/procmail -f %F -d %T"

What do the %F and %T mean? Sometimes, I also see %s. Where can I find the documentation of all the available % options? I have looked at the [fetchmail manual](https://www.fetchmail.info/fetchmail-man.html) , but it doesn't document this.