Pasting in multiple selections
There are many multiple selections across SAP Screen Display.

Example :
1.Go to Tcodes FS10N
    The below screen will be displayed.


2. Click Multiple Selection button
 
3 The below screen will be displayed.


   Enter  Multiple Codes  you want to  include in a 
                                    subscreen
     Enter  a Range of Multiple codes you want
                                    to include in a subscreen.
   Enter  Multiple Codes  you want to  Exclude from a 
                                    subscreen
       Enter  a Range of Multiple codes you want
                                    to exclude from a subscreen.

You can copy and paste mulitple items into those boxes (about 8 boxes) using Ctrl-V like normal. 
More boxes will appear after you hit enter, and you can scroll and paste into them as well. 


But if you want to paste in lots of selections at the same time, you can use the magical “Import from text file”button
The following screen will appeared

To use the Import from text file button, you can either put the content you want to add into a text file and upload it,
or you can copy it from it’s source (SAP, Excel, etc) and then click the Upload from clipboard button.  
This can paste lots and lots of items to you multi-select


Also check out the Multiple Selection button . 
This brings up a search screen that you can do a search and then use check boxes to select mulitple items from the search result