The test area selection is done based on a single layer in the Océ Arizona Xpert Engine. Once the test areas are selected, corresponding test areas are cropped at exactly the same locations from all the other layers. When you have different orientations for any of the other layers (i.e. for a block out) the front and back content may not match when sampling. Likewise, the content may not match if you have multipage documents with different orientations for each page content.
When front and back image registration is important when sampling, prefer symmetrical selections when you select the test areas.
When multiple test areas are needed, the test areas are merged into a single image based on the preferred direction when you select the test areas. In this case, when you prefer left right and you need to flip horizontally one layer, the test areas on the front will not match the positions of the test areas on the back.
When multiple test areas are needed for double-sided applications, prefer the Bottom Top direction and make sure that the width of the areas is the same for all test areas.