Dimensions defined as a percentage
This value is for dimensions defined as a percentage of the overall display dimensions. For example, if using a Percentage Metric type for a Width measurement of 50.0, against a display width of 1920 pixels, then the resulting value used would be 960 pixels (50.0% of 1920) for that dimension. Whenever a measurement uses this Metric type, the resulting values shall be rounded ("floored") towards 0 if the measurement requires an integer final value.
Dimensions defined in a number of Pixels
This value is used for dimensions defined in a number of Pixels.
See
MatterSpecification.v13.Cluster § 6.7.5.4