Many investors have some targets on where they want to invest money. In most cases this target is specified by investment country/region, but this target could be anything (sector, currency, etc). Portfolio Slicer lets you assign each symbol "Allocation" value and then in this "Allocation" table you can specify targeted percent values. It is extremely important that sum of all TargetPercent values would be equal to 100 (percent), otherwise allocation related reports will not work properly.
In above example investor is aiming to have 20% of investments in Canadian stocks and 80% in US stocks. Portfolio Slicer generates report that shows how your actual allocation is different from your targeted allocation. Some Portfolio Slicer users choose allocation targets and then once or twice per year sell "winners" and buy "looser" to make sure that investments match targets. In Canada popular website that describes this approach is "Canadian Couch Potato".