Read this: At launch, the Xbox 360 was available in two configurations: the "Xbox 360" package (unofficially known as the 20 GB Pro or Premium), priced at US$399 or GB£279.99, and the "Xbox 360 Core", priced at US$299 and GB£209.99. The original shipment of the Xbox 360 version included a cut-down version of the Media Remote as a promotion. The Elite package was launched later at US$479. The "Xbox 360 Core" was replaced by the "Xbox 360 Arcade" in October 2007 and a 60 GB version of the Xbox 360 Pro was released on August 1, 2008. The Pro package was discontinued and marked down to US$249 on August 28, 2009 to be sold until stock ran out, while the Elite was also marked down in price to US$299.

What was the Xbox 360 Core package unofficially known as?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable