ONE MOMENT IN TIME: On May 16 Arista is scheduled to issue Whitney Houston's two-disc set, "Whitney: The Greatest Hits" (for a complete track listing, see Newsline, Billboard, April 22). The collection will be preceded, on Tuesday (25), by "Whitney: The Unreleased Mixes." 

Comprising four 12-inches, for a total of eight remixes (in all their extended glory!), the special collectors' boxed set prominently shines the spotlight on one of clubland's reigning divas.

Highlights include such commercially unavailable (and much sought-after) restructurings as Jellybean & David Morales' 1987 Classic Underground mix of "Love Will Save The Day," the Dronez's Club mix of "I'm Your Baby Tonight,"

David Morales' Emotional Club mix of "So Emotional," and Junior Vasquez's Club mixes of "How Will I Know" and "Greatest Love Of All."

Making its debut is the Club 69 mix of "Greatest Love Of All," which was done specifically for this boxed set and which is not included on the two-disc greatest-hits collection.