Convention: White, bumpy side of the darkslide means the film is unexposed. After exposure the darkslide is re-inserted with the black, smooth side out. This was
de rigueur for newspaper and studio photographers in the USA when 4x5 film was the common "small-format" size used for reporting and fashion photography and lots of people were involved that handled the holders (photographer, assistant, lab techs, etc.). Photographers in such situations rarely developed their own film; some standard to avoid confusion had to be invented, so Black=Exposed came to be it. This was taught in institutes and training at the time.
Those of us who came to "large-format" photography later, i.e., after medium-format and 35mm film succeeded 4x5 in studios and in newspaper darkrooms, often didn't get taught the convention.
There are those of us (AgX and I and a few others who have posted here), who do things backwards from the convention. That's fine as long as you are the only one handling the filmholders. Still, it does go against the convention
@OP,
Whichever side of the darkslide you choose to mean exposed makes no real difference as long as you are consistent and anyone handling your film besides yourself knows what your do. I'll wager that there isn't anyone else who deals with loading/unloading/exposing/managing your holders anyway.
I number my holders and indicate the frame number using little labels that fit inside the space for notes provided on most holders, or just pasted on a flat surface near the top of the holder if there's not an indented spot for the label. My holders are numbered sequentially; one holder has the numbers 1 and 2, the next, 3 and 4, and so on. Numbering 1A, 1B for the first holder and 2A, 2B for the next, etc., is equally valid and usable. Again, choose a method and be consistent.
I usually reload my holders after every developing session and put them in quart-size (liter-size for AgX) ZipLoc-style bags. If I don't reload the holders, they sit on the shelf or in a box without a bag. Holders don't go into bags until they are loaded. In the rather rare case that I unload one side of a holder and then return the one-side-loaded holder to my bag for use, I'll stick a Post-It note on the empty side with large letters "MT" on it so I won't mistake it.
When exposing film, I enter each different exposure on a separate sheet of an exposure record in my exposure notebook. This is a small 5x7" ring binder. I make my own records that have fields for title, date, place, date loaded, type of film, E.I., figuring exposure compensation for filters, bellows extension and reciprocity plus a matrix for showing what I placed where and which development I intend (and which paper grade I'm aiming for), notes, etc., etc. If I take multiple exposures of the exact same thing, I'll put all those frame numbers on one sheet. If I take two similar views of the same subject, I'll often do the same, with the note "2 views" or the like. Since development and film type are entered on the exposure record, these go into the darkroom with me when I develop so I can make sure I'm unloading the right frames to get any particular development.
To further avoid double exposures, in addition to flipping the darkslide to show that a frame has been exposed, I always put the frame to be exposed into the ZipLoc facing the clear side of the bag, i.e., the side without any writing or fields for entering information (bags usually come with a large white rectangle for writing on with permanent marker). When I start with a holder with both frames unexposed, the lowest number faces the clear side of the bag. After exposure, I place the holder back in the bag with the opposite side facing the clear side of the bag. So, when I have a one-sided holder, I make sure that in addition to the Post-It with "MT" on it, that the side to be exposed faces the clear side of the bag.
Since I number my holders, I use them in order (unless there's a real good reason for skipping a frame). So, after exposing an even number, the holder gets moved to the exposed pile in my camera bag and later transferred to the exposed side of the cooler I keep my holders in (I've got a large cooler that holds 50 holders).
As for which film is where: I only use two, or sometimes three, kinds of film, so I can usually get by with just making notes to myself or using Post-Its inside the ZipLocs. However, for those that use lots of different films including black-and-white and color, I recommend what AA and others did: At the time of loading the holder, fill out the exposure record for that holder with the date of loading and the type of film, personal E.I., etc. Then you'll have all the info you need for reference for any particular holder.
That about covers it. Sorry this got so long; it takes a lot more to describe it that to actually implement.
Best,
Doremus