Mapping Services Facility › Map Source Definitions › Data Tagging › ASN.1 Tags

ASN.1 Tags

Maps can be developed from ASN.1 for the purpose of driving a transfer syntax, such as BER, in order to communicate in an open systems environment. The ASN.1 definitions describe how the data is serialized for transmission, and how each data component is tagged so that data items can be distinguished.

An ASN.1 tag consists of a tag class, and a tag number. There are the following ASN.1 tag classes:

• UNIVERSAL tags—are defined by ISO bodies.
• APPLICATION tags—are unique throughout an application.
• PRIVATE tags—are defined by private agreement.
• CONTEXT-SPECIFIC tags—have meaning in the immediate context only.

The tag number is an integer value greater than 0.

When an ASN.1 tag is encoded both the class and number are used to create a unique value such that the class and number remain separately decipherable.