ISO/IEC 8825-2:2015 specifies a set of Packed Encoding Rules that may be used to derive a transfer syntax for values of types defined in Rec. ITU-T X.680 | ISO/IEC 8824-1. These Packed Encoding Rules are also to be applied for decoding such a transfer syntax in order to identify the data values being transferred.

The encoding rules specified in this Recommendation | International Standard:

- are used at the time of communication;

- are intended for use in circumstances where minimizing the size of the representation of values is the major concern in the choice of encoding rules;

- allow the extension of an abstract syntax by addition of extra values, preserving the encodings of the existing values, for all forms of extension described in Rec. ITU-T X.680 | ISO/IEC 8824‑1;

- can be modified in accordance with the provisions of Rec. ITU-T X.695 | ISO/IEC 8825‑6.