The status value of a KPI is numerical and can be shown with a value format like any other numerical value in BI Office. Using the format string drop-down in the Custom KPI designer, users can select a predefined format string or supply their own custom string formulation. Custom format masks need to conform to the standards described by Microsoft in the page:
When a status value is displayed in a Gauge, the number is formatted by default as described above. However, if there are screen real-estate issues (i.e., the number is too big for the space), the BI Office heuristics engine will attempt to abbreviate the value using a combination of significant digits for values below 0, and "thousands rounding" for values above 0.
NOTE: In some situations, the original status format mask may be lost.