On all my systems that key (above 7) is numlock. No idea what it is on yours.
And what does NumLock on a Mac??
If you have a numeric pad it should switch from numeric to cursor control (arrows). The 5 key would be used for a mouse click. I think the last time I use a numeric pad on a mac was back in system 6 or 8.
The crossed-out rectangle might mean “clear” which is what that key has been used for on Macs for quite some time now. I don’t think “numlock” even has any meaning any more. My MacAlly Icekey has a numlock and an LED indicator, but when I press it the light doesn’t come on. These days, I don’t even know if Clear even does anything outside of Calculator.
using an IBM (what I have connected right now) hitting numlock (OSX 5.8) lets the numbers move the cursor up and down, left and right, through the text.
I’ll have to try that on my UniComp Model M when I get home. And I’ve been finding other places where “clear” does something. It will remove the selected row in OmniFocus, or if text is selected it will delete the text. If there is no selection, nothing happens.
This key does nothing. (We are talking about a standard iMac keyboard, out of the box.) And surely it has no Numlock function - whether you press it or not, a 4 is always a 4 (thank God!), no cursor movement. And it did NOT clear any of the entry fields I encountered during my experiments.
So, the Mac has its useless keys as well… q.e.d. 
Maybe you have found the illusive “any” key.
Speaking of completely useless, potentially Any Key candidates, this IceKey keyboard has a blank key to the right of the right-side Control key. At first I thought they did that so that they could, if they wanted, make a Windows keyboard which has four modifiers on the right (well okay, one isn’t really a modifier but a right-click), but then I investigated the key with a tool that lets you see key codes and it’s completely dead. It’s a fully mechanically functional key wired up to nothing at all. Like someone in engineering didn’t get that memo, and nobody in QA was paying attention.
They used the template for FN (function) key. That was standard on Star systems (made by Xerox) in the 80’s and some early XT systems I have seen laying around (no tin my basement thankyouverymuch). It allowed the standard function keys to do the cut/copy/paste, advanced program features (these systems were typically purpose built), and macro sequences. The extra key allowed the function keys to still be used for “regular” operations outside the original design spec software.
But who cares?
Actually looking at my wireless keyboard my function keys do different things based on when I hit the function key!
I was rather disappointed that it doesn’t do anything. I was hoping to give it some useful seldom-often task, like say, firing off an angry letter to Apple every time NSTextView borks.
i figure you would have had it post a link to the scrivener FAQ. Maybe the network drive thread, but certainly the FAQ.
Command-WeirdEmptyNothingAnyKey = FAQ. When needing to be a little extra authoritative, Command-Control-WeirdEmptyNothingAnyKey = FAQ with bold tags around it.
Just to bring this back on topic. Ha.
If we are being back on topic, the real glory to the illogical (OP opinion) method here in OSX land is that I can actually make my own shortcuts. As part of the OS. And I can apply whatever logic I want. Which means that I don’t need alt--arrow-arrow-arrow to find things I want.
Just looking at my little wireless keyboard the number of possible key combinations is staggering. CMD, Alt, Ctl, FN, the various combinations of those four, then the shift key… Someone with a brain should do the math on how many possibilities there are.
Well, the Mac (at least with Leopard on up) also has another feature that makes function discovery remarkably easy: Menu search, from the Help menu.
If I remember my math permutations properly…
assumptions
• User can hold down 4 keys with each hand.
• one hand will only be used for command keys
• All combinations are possible with the other hand (meaning we do not disallow difficult combinations)
• We exclude the shift key.
• We have 24 alphas and 10 numeral, all other keys disallowed.
I believe that leaves us with 4!(34!-30!). Based on the unrealistic answer of 7.0855808108819e^39 I think I did something wrong.
I think TextMate might be just shy of having that many, actually. Though, now that I think about it, TextMate employs a feature which is actually quite similar to Emac’s Ctrl-n-o-c-1 style sequences in that a keyboard shortcut can actually access a great number of features which appear in a pop-up menu that can accessed with a keystroke from there. This allows a kind of logical grouping that I like. A simple example: All of my MultiMarkdown boilerplates can be generated with Ctrl-M, or my text cleaning scripts with Cmd-Opt-Ctrl-R.
That is one of the reasons I never got into emacs. Vi did everything I needed. elvis was as advanced as I could stand. Then again I am just a simpleton who can’t even spell his own name. I am ok with needing to hit the mouse every now and then.
Ok, enough talking of keyboard hardware. Back to the software side: is there any hope Scrivener will implement a totally free keyboard shortcut assignment, as in Nisus Writer? I’ve my own mania, and my fingers often howl to type that particular key sequence.
Paolo