Diagnosis
You have positioned the cursor between two fields or on a line whichdoes not support the function Copy.
You can only transfer codes with this function in the current list.

System Response
The function was not performed.

Procedure
If you want to select a code, you must position the cursor in a fieldon a code line before calling the function.
If necessary, you must explode any higher-level hierarchy nodesbeforehand. To do this, position the cursor on the symbol + ,and then call the choose/explode function.