Selects all modules in the current letter.

Among many other options, one of the more common reasons to select all modules is to copy them to another letter (Shift+A selects and copies all modules to the Clipboard). You can easily do this by then clicking on another instance of this same letter and pressing Shift+V. The modules selected in the original letter are then copied to the new letter. Make sure that the destination letter does not have any modules in it already.