What information should be included in a DTV visa invitation letter for training Muay Thai in Thailand?

A user is seeking guidance on applying for a DTV visa at the Thai embassy in Vientiane, Laos, specifically through Muay Thai training. They request a sample invitation letter from a training school, as this is their first experience with the process. Responses from the community include offers to provide example letters, a list of required documents (such as company registration and proof of payment), and advice to obtain the invitation from a recognized Muay Thai training school to ensure compliance with embassy requirements.