does PointCloud2 have redundant fields?

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I'm thinking of hijacking the PointCloud2 message to display a set of data. Each data point has position, orientation, and another integer value. I see that I have to tell PointCloud2 the width/height of my data (in my case, Nx1), and the fields and their sizes (in my case, 7 float32 and 1 int32)

Given this, what is the point of the row_step and point_step? Why do I have to calculate those and add them to the message? I seems like redundant information, where:

point_step = field size
row_step = field_size * width