Group 1 - The article discusses the presence of specific keywords such as "snow," "pet," and "quiet" next to certain train services on the 12306 platform, indicating special features for travelers [3][4] - The keyword "snow" refers to a service that allows ski enthusiasts to carry ski equipment with dimensions exceeding 130 cm but not exceeding 200 cm, facilitating convenient travel for skiers [4] - The keyword "pet" indicates that travelers can transport up to two healthy domestic pets, such as cats or dogs, with specific weight and size restrictions, enhancing the travel experience for pet owners [4] - The keyword "quiet" signifies the availability of a "quiet carriage" service where the onboard video system is muted, and staff provide services in a low voice, catering to passengers seeking a peaceful environment [4]