Abstract: In the measurement of properties of a wafer substrate, such as Critical Dimension or overlay a sampling plan is produced defined for measuring a property of a substrate, wherein the sampling plan comprises a plurality of sub-sampling plans. The sampling plan may be constrained to a predetermined fixed number of measurement points and is used to control an inspection apparatus to perform a plurality of measurements of the property of a plurality of substrates using different sub-sampling plans for respective substrates, optionally, the results are stacked to at least partially recompose the measurement results according to the sample plan.

Abstract: The invention relates to a catamaran-type sail boat comprising several inclined mast-like elements rotatively mounted at their lower ends and upper ends respectively by appropriate lower connecting mechanism and upper connecting mechanism, the masts being provided over at least a portion of their length with a fin rigidly connected to the masts, the fin working as a sail. Angular rotation positioning mechanism is provided to rotate the rotatable masts provided with the fin so that the boat can be driven at will.