This is a very interesting question. And you have really good observation. :>
Excel has two functions:
1) REPEAT
2) REDO
They're different.
When you did something, you can press the command Ctrl+Y to repeat the
previous step. However, the REDO button remains inactive most of the time.
Why? Because you haven't UNDO something.
The REDO button is to REDO a step you just UNDO.
So, let's do a simple test.
1) Type something in some cells.
2) Select one cell. Right-click. Choose Clear Content.
3) Select another cell. Press Ctrl+Y to repeat.
4) Observe the REDO button still inactive.
5) Now, press Ctrl+Z to undo.
6) Observe the REDO button. Now you can REDO the previous UNDO step!!
Regards,
Edwin Tam
(e-mail address removed)
http://www.vonixx.com