Rule Three: “When referring to Thunderbird or Firebird … make sure to use the project name with Mozilla pre-pended as “Mozilla Thunderbird” or ”Mozilla Firebird” instead of Mozilla alone or Firebird/Thunderbird alone.”
The document does not keep its own rules.
On just the next line: “our primary development on the Firebird and Thunderbird projects”
Sorry, it seems funny to me at this hour of the night. :)