题目内容：
根据下面资料，回答题 Digital Video Express
①A pay-for-play system for video DVD will emerge by summer as an alternative, and possibly a competitor, to the DVD format currently available.
②The new system, called Digital Video Express( Divx), operates like a DVD player, except
for the specially coded discs. These will cost $5 for initial viewing over a 48-hour period and can beviewed again for additional fees and even purchased for unlimited viewing.
③Divx combines the service of a video rental( 出租的)store with the operation of a pay-per-viewchannel. Unlike a rented videotape, though, the Divx disc needn't be returned. Customers can retainthe disc for replay in the future at an additional fee, or simply throw it away.
④Subsequent plays,or the purchase of unlimited-viewing rights, are billed to the customer'sDivx account and charged to a credit card. The player' s built-in memory keeps track of all Divxplays, and sends this information by toll-free phone modem(调制解调器) to the Divx record-keepingcentre. Each Divx disc and player has a unique identification code, so the system knows which discshave been played and where.
⑤Some Divx discs could be converted for unlimited play at a price likely to be lower thanbuying a conventional DVD. Others, called Divx Gold, would be sold from the beginning for unlimitedplay without further charge. Although conventional DVDs will run in a Divx player, conventionalDVD players will lack the decoding (解码) and communications ability to play Divx discs. Divxplayers will be offered by Panasonic, RCA, and Zenith.
The Divx disc is different from the rented videotape in that once offered ,the Divx disc______.
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