Here is the breakdown courtesy of Ibanez Collectors World.
F is the production factory which stands for Fujigen.
The first digit will be the last digit of the year, ie. The last 5 numbers will be the consecutive number denoting production count for the year with the caveat that each month will start at predetermined intervals of 3000 or 5000, etc.
In cases where generic non model specific plates are used the 4 digit number is just the consecutive number of that plate which could have made it on possibly 10 different models.
- JEM plates are 6 digit and the first 2 digits is the production year while the last 4 is the consecutive number JEM built from inception. Except for the very first batch of 90' UV plates that began 00, UV plates are also dated by the first 2 numbers. A Universe plate 912787 would denote a production year of 91 and the 2787th Universe built.
- Cort serial numbers are denoted with a C prefix followed by either 7 or 8 digits.
I'm not sure what year the changeover occurred but using the formula it will be easy for you to tell.
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].
I do not know how accurate the system is but the few I've run have worked just fine. Plate serial numbers have nothing to do with headstock serial numbers.
;) This page is for dating Ibanez guitars built in Japan only.