How do I make a choice/dropdown list for a tag?

[Thijs_Alphen]

Since I rip mainly classical music for use with Audirvana, I use the Tags Period and Style.

Example
Ludwig van Beethoven, 33 Veränderungen über einen Walzer von Anton Diabelli op.120 ('Diabelli Variationen')

• Genre: Classical
• Period: Romantic
• Style: Solo instrumental
• Instrument:

...