ETERM, EPL and Xintianyou are all black-screen operating systems for air tickets. Although \x0d\ is different, the application instructions are the same. They are all operated by the simplest instructions, such as AVH, SD and nm. \x0d\ A system used to query the prices of air tickets and flights and to complete the reservation and ticketing operations on the system. Domestic and international air tickets can be issued. I just need to recite a lot of "three-character codes". \ x0d \ x0d \ is called "black screen", I think, probably because the interface you operate is black and the input and system-generated instructions are green. \ x0d \ x0d \ air ticket black screen system is generally used by airlines or professional air ticket booking agencies, and you must have an account to log in. \ x0d \ x0d \ As long as you have basic computer and English skills and work hard, you are easy to learn and use.