Abstract Syntax Notation One (ASN.1) is a standard and notation that describes rules and structures for representing, encoding, transmitting, and decoding data in telecommunications and computer networking. The formal rules enable representation of objects that are independent of machine-specific encoding techniques. Formal notation makes it possible to automate the task of validating whether a specific instance of data representation abides by the specifications. In other words, software tools can be used for the validation.
It also has Wiki Link.
I strongly recommend you to visit the below link for described information. The Link is from International Telecommunication Standardization.
Why ASN.1 is required