Please sign me up for this. Though I should warn you, I've been journaling for 9 years and sometimes there's no cure for bad handwriting!
Dear Diary, Today lil followed me! It was the best day ever! Love, Lou (except instead of typed lines, it's the usual tangled scrawl)
This. I've been keeping a journal for about 15 years consistently, have probably 4-5 notebooks filled per year... and I'm pretty sure I would be needed to "decode" them should they ever fall into the wrong hands.
If they fell into the "wrong" hands, better to not decode them. Just make something up. :-) Going back and reading old journals (or old snail mail letters) can be interesting (or frustrating if the writing is too messy). I was reading an old journal the other day from when I was in my 20s. I wrote a line about how frustrating my affairs with T, D, and H were. I had no idea who T, D, and H were. I read through the whole journal looking for some reference to T, D, and H - and there was nothing. Eventually I figured it out. T. D. and H. stood for -- Tom, Dick, and Harry - in other words, a reference to men in general.
Yeah, write neatly AND explain your abbreviations so your biographers don't suffer too much.