Application Control Service Element (ACSE) belongs to the OSI service elements, the Common Application Service Elements( CASE), of the application layer. ACSE controls the establishment and termination of connections and is responsible for the termination and maintenance of connections, the so-called associations, between two application work units.
ACSE can thus create and trigger associations. That is why the acronym ACSE also stands for Association Control Service Element. Before the connection is created, the context of the application is agreed between the communication partners.
Basically, an application process accesses an application service element via a user element. To a service element belongs a certain number of language elements for the execution of the services. These are referred to as abstract syntax. The language elements of an abstract syntax are represented for transfer in the transfer syntax to be agreed between the representation instances. In OSI standardization, the only data description language used for the formal description of the abstract syntax is ASN.1.