Yes well.....In any case, something anyone might want to consider (as few actually swap out their lines regularly like they should
) would be to not trust so much in your electronics (yes I'm old), and do it the old fashioned way.
First off, marking your line is a fine idea right up until you cannot recall what in the the ingenious "code"
is that you developed. Heck, you're so clever that the NSA & CIA will spend the next 20 years cracking it. The trouble is, besides your Commodore-64 just having crashed, you just drank that one-too-many beers in your life, and that lone brain cell that remembered the info has just been wiped clean.
So, instead of codes and so on get yourself some waterproof stickers and a pen (this time keeping it simple) and write something like "WFF-5wt" or "WFST(10)-5wt" and so on, then stick it to the reel foot, inside the housing, or on the back of the spool.
Now I myself am a "some-reels, lots-of-spools" kinda guy. Each reel has a case/pouch, and inside that case I keep a spool keeper with the line info written on it (neoprene strap with a slider). All of my spare spools (so varied lines) have a spool keeper around them marked as well....So, when I swap spools, on the old spool goes its keeper, the new spool's keeper into the bag..and so it goes.
My old Battenkill disk drag literally has 6 spools of 3 different line weights for it and using the system above there is no confusion....The keepers never get wet (well except when I go unintentionally swimming) so the ink won't run.......and when their batteries go dead I just replace them (okay, that last part is a lie).
Think on it.....as my spool keepers, topo map and compass seem to run forever compared to an I-phone and GPS.....Besides, when the Martians attack I'll be able to keep fishing while everyone else goes "awww cwap, my phone is dead!"