OP Codes and the push to confuse.
A certain group of BTC Core developers have their (one day but not in my lifetime) sidechains that will enable OP_Codes that have been left broken in BTC (and which are working in BCH).
In this post I will pick on the lack of thought of some of these by demonstrating how you can create the same outcome without a new OP_Code.
Dup from Alt Stack
This copies a value to the Main from Alt stack leaving the Alt stack as it was.
Swaps the Main and Alt Stack.
We have now swapped the stack locations.
Dup TO ALT Stack
This copies to the Alt Stack while leaving a copy on the main stack. We do this as:
The command works as: