The needed properties of a digital watermark depend on the use case in which it is applied.

Unlike metadata that is added to the carrier signal, a digital watermark does not change the size of the carrier signal.

Usually it can be checked by holding the cotton paper up to the light and looking just below the watermark for a number.

Its binding is Turkish, and appears to be original but the paper has an Italian watermark, which has been dated between 1563 and 1620.

A watermark is an identifying image or pattern in paper that appears as various shades of lightness darkness when viewed by transmitted light (or when viewed by reflected light, atop a dark background), caused by thickness or density variations in the paper.