Calculating and Modeling Common Parts of Software Product Lines

A waterbed and holder assembly for use therewith wherein the holder assembly comprises a U-shaped base member for being secured to the waterbed's frame, an expandable, resilient member (e.g., elastic fabric material) for being secured at one end to an article of the waterbed's bedclothing (e.g., sheet) and for being releasably secured at the other end to the U-shaped base member, a first retention means (e.g., snap fastener) for providing the resilient member's releasable securement, and a second retention means (e.g., removable cover) for engaging the resilient member to retain it against the base member. Positioning and securement of the article of bedclothing in an expeditious manner is thus provided.