There are many different explanations of floating units, also sometimes referred to as flexible unit.  One scenario would be where you purchase floating units that rotate in increments of time, for example your two week period, would move up or down the in the calendar location each year.  A second example would be where your floating unit would be selected by choice in order of priority of the date you purchased the property.  Another example, you are the first person to purchase your vacation fractional interest and you purchase two floating weeks, in the first year when the new calendar is set you would be asked first to choose your floating weeks, the second purchaser would have second choice to select their floating weeks and third person and so on through all the owners in the fractional ownership group.  In the following year as you were first in the selection process you would drop to the bottom of the ownership list and the second person gets first choice of the floating weeks and so on until each person in the fractional interest ownership group has moved through the rotation of first choice.  In some of the larger vacation fractional ownership properties ownership access is to a pool of identical residences, rather than the single specific unit that the members own.