30 mA for all domestic circuits up to 20 or 32 A in most parts of Europe, no requirements for more sensitive protection that I'm aware of but keep in mind that Europe is a continent with dozens of independent countries, almost each of which has its own electrical regulations. Most, if not all of those are based on the CENELEC harmonisation documents but with countless national additions and exceptions. In commercial and industrial installations usually 30 mA for socket circuits up to the limits I mentioned above, not required for hard-wired appliances and lighting circuits, unless classified as special locations (primarily high fire risk, e.g. woodworking, storage of flammable materials, etc.). 10 mA is readily available but nothing smaller.
The actual implementation depends on local customs and, to a degree, cost - one main RCD, multiple RCDs or individual RCBOs can be used.
