Extending cut-and-paste: CTRL+SHIFT to add modifier keys

I want to talk about some more complicated cut, copy and paste operations, but first I need to talk about how you'd enter them in.

You'd need to press additional keys to specify the additional parts of the operations, for example:

     CTRL+V+3

to paste the third item on the clipboard.

Except that you can't just press that key combination, for as soon as you've pressed CTRL+V, it would paste the latest clipboard item -- before you'd got a chance to specify the 3.

To indicate they're using an extended operation, the user could initially hold down SHIFT as well as CTRL. Once they'd initially done this, they could release the SHIFT key and then enter the rest of the keys in their command.

So for that same operation again:

     CTRL(+SHIFT)+V,3

which means, press CTRL and SHIFT together, release SHIFT, and then press 'V', then '3'.

(The way Enso works would be more conducive to entering in variable length cut-and-paste operations, but that's another story).