This expression is mentioned in one or more threads, but it seems important enough perhaps to add it to the dictionary definitions?
(The following is taken from the glossary found on the website Theatrecrafts.com)
RIDER
(Technical Rider) A rider lists all of the requirements (logistical and technical) that an incoming company requires a venue to provide on arrival. The rider should cover lighting, sound, staging and dressing room requirements, and should describe the show in enough detail that the venue can take decisions about how to prepare the venue.
(The following is taken from the glossary found on the website Theatrecrafts.com)
RIDER
(Technical Rider) A rider lists all of the requirements (logistical and technical) that an incoming company requires a venue to provide on arrival. The rider should cover lighting, sound, staging and dressing room requirements, and should describe the show in enough detail that the venue can take decisions about how to prepare the venue.