The mainstream ones are: number of layers, length, width, shape, plate thickness, minimum spacing or line width, minimum through hole size, whether there are blind buried holes, whether to open windows through holes, screen printing green oil color and so on!

The more critical master will have many requirements, such as aperture tolerance, copper thickness, plate current coefficient and so on. The worst thing is that there are many demands but not much money. Life in this world is hard!