# What is the ASTERIX terminology for an atomic piece of information?

The ASTERIX standard defines the smallest piece of metadata information:

Data Item: The smallest unit of information in each Data Category.

And the implementation equivalent:

Data Field: Physical implementation for the purpose of communication of a Data Item, it is associated with a unique Field Reference Number and is the smallest unit of transmitted information.

But, neither of them are atomic. The most common example is Data Source Identifier (SIC/SAC) which contains two pieces of information: SIC and SAC. For instance, such a Data Item is defined in the 048 Category:

Data Item I048/010, Data Source Identifier Identification of the radar station from which the data are received. Two-octet fixed length Data Item.
bits-16/9 (SAC) System Area Code
bits-8/1 (SIC) System Identification Code

So my question is: what is an atomic (minimal) piece of information called in the ASTERIX standard?

• There is no official name for that unfortunately. I call it element. – DeltaLima Sep 25 '17 at 7:13
• The spec does not appear to define what is an atomic piece of information, likely because it assumes the implementer already knows the answer. From what I see, the equivalent of what you seek from the point of view of the spec is the data item. – Juan Jimenez Oct 11 '17 at 21:09