ENTER↑ is a misnomer, long live ENTER:

[hansklav]

(07-06-2014 11:35 PM)Didier Lachieze Wrote:  If you're interested in HP calculator history, we can trace back the origin of the "Entry RPN" before the HP-28C to the HP-41 translator pac for the HP-71b. Bill Wickes who developed the HP-41 translator pac as an "after-hours" project was also the software project manager for the HP-28C/S [1].

In an article published in January 1985 in CHHU Chronicle ( THE HP-41 TRANSLATOR PAC FOR THE HP-71) Bill Wickes introduced the command line and the removal of the stack lift disable:

Thanks for this very interesting article!

It gives insight into both the primordial history of what would become the RPL lineage, and into the fact that two functions were merged into the ENTER↑ key of the HP-35: digit entry termination and duplication on the stack.

To the novice user of RPN especially the first function, digit entry termination, is important to be able to learn when to push the ENTER↑ key (and moreover when NOT to push it).
The label ENTER: on this key would stress this function, "ENTER NEXT:", so only press ENTER: when you have to key in another number before pressing a function key.

To the seasoned user and programmer the aspect of stack duplication may be more interesting, but then this user hardly needs the labelling of the key as a mnemonic.

Hans