3 additional commands which are sent only by server:
	1. execute script directly
	2. bind function to id
	3. execute function bound to id (with optional payload)

Scripts are sent to client as bytecode.

about 2 and 3:
	- It's worth noting that no ID is needed at all.
		We can just bind some general callback for later execution and this
		callback could read specific part of payload and by that know which
		command to run. However, Lua does not have switch statement and execution
		of lot of "if" statements just to know which command to run is not optimal,
		so maybe having function ID is not bad at all.
	- Binding a function without arguments to some ID is bit useless, isn't it?
		We want to pass some arguments to bound functions and this can be
		accomplished by having some payload after function ID.

How I see it in scripting:

minetest.register_on_clientside_call(id, callback)
	callback is a function or string
	string is sent as is, but callback is converted to bytecode (also a string)
		actually string.dump(f) converts a function f to bytecode

example:

-- direct
minetest.clientside_execute(function()
	local player = minetest.get_current_player()
	minetest.chat_send_player(player:get_name(), "Hello")
end)

-- indirect
minetest.clientside_bind(10, function(payload)
	local player = minetest.get_current_player()
	minetest.chat_send_player(player:get_name(), payload)
end)

minetest.clientside_call(10, "Hello")