Plane groups - International Crystallographic Tables

How do we use the international crystallographic tables? What information do they provide? How can we use this to: 1) recreate a 2D pattern, 2) define different "positions" within the unit cell (Wyckoff positions), 3) determine the composition of a 2D material?
This is a step-by-step guide to the contents of the international crystallographic tables.

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thanks for the video!! Question:how do we know if the wyckoff site are occupied? to know if we could apply the special relection conditions