This is the 11281st most frequent Russian word.
действующем
The Russian word "действующем" means "acting," "operating," or "current" depending on context.
In this sentence, 'действующем' is a participle derived from the verb 'действовать,' meaning 'to act or to be in effect.' It describes a law that is currently in action or enforced.
Сегодня я читал статью о действующем законе.
Today, I read an article about the current law.
Here, 'действующем' is describing the theater as being currently operational or active.
В действующем театре прошел новый спектакль.
A new performance took place in the operating theater.
In this usage, 'действующем' is modifying 'регламенте' (regulations) to indicate that these regulations are currently in force.