The Empty band has only one special property - SizeMode. This property indicates the behavior of the Empty Band on the bottom of a page. There are 4 values of the property: IncreaseLastRow, DecreaseLastRow, AlignFooterToBottom, AlignFooterToTop.
The IncreaseLastRow indicates that if, when filling the page by an Empty band, there is a free space to partially output an Empty Band, then it is possible to increase the last row. The picture below shows this.
DecreaseLastRow. The last row of the Empty Band will be decreased by height. The picture below shows this.
AlignFooterToBottom. If there is no free space for the Empty band then this band is not output. The picture below shows this.
AlignFooterToTop. (this is the default value of the SizeMode property). The Footer Bands will be output on the bottom (the PrintAtBottom = true) and moved to top to fill the free space of the Empty Band. The picture below shows this.