IBM 3270 Manual page 150

4.
Press the Alt and CrSel keys to mark the
upper left corner of the copy.
In a host or notepad window, the copy will
occupy the space shown in reverse video with
the corners marked. In a PC window, only
corner marks show the space for the copy.
Twinkle, twinkle, little star -
How I wonder what you are.
High above the sky so bright,
- wish I could remember the last line.
This message appears:
Source and Target areas are defined. Use the Enter key to copy.
WSCTRL COpy
5. If you are not happy with the position of the
copy, go back to step 2, and choose a new
place for the copy.
Chapter 10. Copying Text from Window to Window 10-7