All paper produced by paper machines as the Fourdrinier Machine are wove paper, i.e. the wire mesh that transports the web leaves a pattern that has the same density along the paper grain and across the grain. Textured finishes, watermarks and wire patterns imitating hand-made laid paper can be created by the use of appropriate rollers in the later stages of the machine.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): What leaves a pattern on the paper that doesn't have a consistent density width and lengthwise?
unanswerable