I mentioned a few days ago that the team has been immersed lately in improving the Office 2007 keyboard model. We got a lot of constructive feedback around the model from Beta 1 and so we're hard at work addressing it for Beta 2.

Today, I want to just throw out a minor but important detail of the overall design for discussion to see what you think.

As I mentioned in my original post on the keyboard model, the first step of using the keyboard with the Ribbon is pressing a letter to navigate to the tab which contains the control you want to use. For instance, many apps have a Review tab, and pressing ALT+R puts you in a mode to access the commands on the Review tab with the keyboard by pressing subsequent letters.

One of the questions we're trying to answer is: What letter should we use for the first tab of each of the Office 2007 programs?

Allow me to lay out the pros and cons of some of the myriad possibilities.

The first decision: is it important that the first tab of all Ribbon apps share the same accelerator?

The argument for yes says that certain commands, such as the Clipboard, Find, Bold, and Italic are almost always on the first tab and therefore if you assign the same letter to the first tab everywhere, then keyboard accelerators are more portable across apps.

The counter-argument is that the majority of the features present on the first tabs are actually different--Excel has Sort and Conditional Formatting, while Word has Styles and PowerPoint has Slide Layout. And the commands which are consistent already have well-known keyboard shortcuts (CTRL+F, CTRL+B, CTRL+I, CTRL+X, etc.)

If you do want a common first tab letter, the first thing that comes to mind would be to pick a letter with a mnemonic hook. For instance, "F" is good for File because it's the first letter of the word. However, the names of the first tabs of each of the apps don't have any letters in common. Word is "Write," Excel is "Sheet," PowerPoint is "Slides," Access is "Data." And Outlook's are totally variable based on the item type. So using a letter present in all of the words would be impossible, because there aren't any.

Maybe instead we should optimize around picking a common letter that's easy to type; after all, probably 90% of keyboard accelerators in Office 2007 will start with this keystroke. Millions of people will type it millions of times a day.

So maybe something on the home row of the keyboard? Something on the left side so that you can hold on to the mouse? Dig up the research about which letters are easiest to type? "F" and "J" have the little "home row" dots on them, but F is used for File. Wouldn't people laugh at us if we gave the first tab "J" even if there's a good reason?

"H" is another possibility, since it's easy to type, you could imagine it stands for "Home," and sometimes we think of the first tab as the "home tab" because it's where you will spend most of your time.

Or maybe you go with "S" because it is the first letter of the name of two of the first tabs (in Excel and PowerPoint). But, if you get used to hitting ALT+S to access the most common commands, you might get tripped up because in Outlook, the same shortcut immediately sends the e-mail you're working on. So maybe "S" isn't the best idea either.

Maybe we should use some other easy-to-type combination, say ALT+SPACE or ALT+ENTER or ALT+ALT even. Unfortunately, all of them already have well-established behaviors in Windows or Office which cannot be changed.

There are other factors which go into the design as well, such as localization issues and the fact that some of the letters are reserved and cannot be used. But for simplicity's sake I won't get into those here.

So, what should we do? Is it important that the first tabs share a common letter, and if so, which one should we use? Or, should we pick the letter which works best for each program (probably mnemonically) and have inconsistency between the apps? Or something else we haven't thought of yet?

Which letter is better?