Universität Bremen TZI TUD Dresden University of Technology The Concise Binary Object Representation (CBOR, RFC 8949 == STD 94) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. CBOR does not provide any forms of data compression. CBOR data items, in particular when generated from legacy data models, often allow considerable gains in compactness when applying data compression. While traditional data compression techniques such as DEFLATE (RFC 1951) can work well for CBOR encoded data items, their disadvantage is that the recipient needs to decompress the compressed form before it can make use of the data. This specification describes Packed CBOR, a set of CBOR tags and simple values that enable a simple transformation of an original CBOR data item into a Packed CBOR data item that is almost as easy to consume as the original CBOR data item. A separate decompression step is therefore often not required at the recipient. // (This cref will be removed by the RFC editor:) The present // revision -16 is intended as input to IETF 123, to address the // discussion about the use of simple values as reference items // during the 2025-06-11 CBOR interim meeting. It contains a number // of editorial improvements as well as the new concept of an // integration tag; it is for discussion whether the latter should or // should not be added to Packed CBOR. The wording of the present // revision continues to make use of the tunables A/B/C to be set to // specific numbers before completing the Packed CBOR specification; // not all the examples may fully align yet.