With 'Measure Alternating' the linear entities you select serve as axis lines for rows of blocks. You can specify how many rows of blocks should be placed. By changing the offset you can change the distance between the rows and by changing the distance you can change the distance between the blocks in a row. The blocks will be placed in an alternating fashion. The offset is an absolute value but the distance is not. When the command is applied to an arc, ellipse, polyline, circle or spline there will be a row on the inside and a row on the outside. To keep a perfect alternation in the blocks the distance on the outside rows will increase and the distance on the inside rows will decrease. The average distance however will be the distance you specify. The blocks can be placed from the start of the selected linear entities but will be placed orientated on the midpoint of the linear entity by default. The alternation will start in one or more rows. With invert you can create an alternation in the opposite way. You can also use it to place blocks between the blocks you placed before.