I'm not sure what year the changeover occurred but using the formula it will be easy for you to tell.
F is the production factory which stands for Fujigen.
An 8 digit number example - C03114373 - translates, 03 = 2003, 11 = 11th month [November], 4373 = 4373rd guitar built in November 2003.
Prior to 11/2011 there are 5 digits followed by a letter.
The letter denotes year, starting in 2010 with A, with a 5 digit production number. Alphabet Production Month (A = January to L = December), Next two numbers are Production Year (09-2009. 5 is UV77REMC [2 is FRM1, etc], Next Two numbers is monthly series number.
Post 11/2011 they changed to alpha, 4 numbers, alpha, the first letter being the month, A for January, the last being the year, B for 2011, C for 2012, etc. - The Guitar Dater Project will decode W, S, I and who knows what other prefixes [factory codes].