The "preview" link in an ebook's Full Record in LibCentral provides a LibCentral user with a 5 minute browse period, per ebook, per user, per 24 hours.
The preview copy of the ebook will open in Ebook Central. The URL for the preview copy appears to be the same URL as a purchased, subscribed, or DDA copy. However, this is a separate copy of the ebook, used only for preview access.
When you have reached the end of the 5 minute preview period, you will receive the message: “Your reading period for this title is over. Please refresh the page.”
After refreshing the page, the availability message will confirm that your preview has ended: "Your 5-minute reading period is over."