All luggage you have, including hand baggage, must be submitted at check-in to airline staff. This requirement is related to the safety of flight. Baggage that is accepted by the airline for carriage under its own responsibility for its safety, marked  with the baggage tag and called registered. A luggage tag should specify your name, address, phone number

Securities and commercial papers, passports and other documents, medicines, breakable objects, jewelry should be carried in hand luggage.
For any luggage exceeding the established norms of free baggage allowance, a payment under the relevant baggage fare is required.
Carrier may refuse carriage of baggage:
things that can cause damage to aircraft, persons or property on board the aircraft;
things, whose carriage is prohibited by laws, rules and regulations of state agencies of any country on the territory, from or through which the transfer is made;
things which by their weight, dimensions or other characteristics may not be transported as baggage;
animals, except dogs, cats and other indoor domesticated animals that are accepted for transportation under the carrier's authorization and under certain conditions in accordance with the rules of such transportation.