Beta and alpha elements

Wikipedia also has an article about Beta and alpha elements.

The term Beta specifically refers to the stage in a software release life cycle when a project is complete and all of its planned features have been implemented into the product.

It is named after the Greek letter Beta, as it is the second stage in the software release life cycle and unlike its previous stage Alpha the developers have tested the software at least once, and some or all of the intended features may not have been implemented into the program yet.

In the Pokémon glitch community

The word "Beta" is usually used in the Pokémon (and Pokémon glitch community) to refer to elements which still exist in a Pokémon game, screenshots, illustrations, or concept art which are normally never used (if at all) in the final game or product. This is sometimes used informally however, as elements such as concept art formally should be considered as part of the project in its Pre-Alpha stage.