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. Unlike its previous stage Alpha the developers have tested the software at least once, and all of the intended features have been implemented into the program, although it is rare that certain parts of these features will remain changed in the final product.

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.