I Should Have Known This Before!
Over the years, I have developed a system for naming files that I find very useful. Here is that system:
xxx = the abbreviation of the category, which is never more than three letters long, i.e. AR = Accounts Receivable, AP = Accounts Payable, J = Journal (because I'm secretly a 14 year old girl), N = Notes (which I edit and published on Clean Sheets and Dirty Girls), etc.
_ = the underscore character
SubjectMatter = a name for the file that I will remember later
yyyy_mm_dd = the date in this format because that way it can be sorted by name on the computer and come up in order. I always write dates in the computer in this way.
0n = zero and a number that increases by one every time I save a file so that I or anyone I am working with can quickly identify the current version of the file, which is the one with the highest number at the end. If I know that the type of document will include a lot of files, I will make this more than two digits long.
For years, I was had been using mm_dd_yy in my file names. Only about one year ago did I finally switch to yyyy_mm_dd, which makes so much more sense because it can be sorted my a computer and have the results appear in chronological order. If I had only been reading the latest from the International Organization for Standardization (I.S.O.) I would have been on to the more useful way of expressing dates years earlier!
Here is the link to the xkcd comic on the subject of correctly formatting dates for all your chronophiles.