Is there an official source about this? I thought it sounds like "fur" with an L. Or FLIR is an abbreviation of something and it should be pronounced as indivi

Is there an official source about this? I thought it sounds like "fur" with an L. Or FLIR is an abbreviation of something and it should be pronounced as individual letters. By the way, English is a bad language to write pronunciation of words in. I had a hard time not to make the "/ɛ/" sound when seeing "ee".