Introduction

This document specifies the NATO ACP240 Attribute Mapping. It comprises one of the additional specifications of the CABE Architecture, as defined in the CABE Architecture Specification.

Definitions

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY” and “OPTIONAL” in this document are to be interpreted as specified in BCP 14 when, and only when, they appear in all capitals, as shown here.

All definitions given in the CABE Architecture Specification are reused for the purposes of this document.

ACP240 Attribute Mapping

The CABE Architecture defines the concept of an Attribute Set, which is a set of key value pairs characterising a CABE Message or CABE Envelope. Below is defined an attribute mapping aligned with the NATO ACP240 architecture and and the STANAG 4774 labelling scheme.

`p` (policyIdentifier)

The p attribute corresponds to the STANAG 4774 policyIdentifier field. It MUST be present and MUST conform to the following ABNF:

  POLICY_IDENTIFIER  = COUNTRY / "NATO" / "PUBLIC"
  COUNTRY            = 3UPPER_ALPHA
  UPPER_ALPHA        = %x41-5A

`s` (sensitivity)

The s attribute corresponds to the STANAG 4774 classification field. It MUST be present. The values for this field MUST be uppercase.

When p is set to "NATO" it MUST be set to one of the following values:

"UNCLASSIFIED"
"RESTRICTED"
"CONFIDENTIAL"
"SECRET"
"TOP SECRET"

When p is set to "PUBLIC", it MUST be set to "UNMARKED".

When p is set to a country code, the valid values are dependent on the specific policy of that country.

`r` (releasability)

The r attribute corresponds to the STANAG 4774 releasability field. It MAY be present. If present, it MUST be a string containing a comma separated list of uppercase values sorted in ascending lexicographic order. A given country code MUST NOT appear twice. The list MAY be empty, in which case it is represented as the empty string.

These requirements are intended to create a canonical representation for a logical set of country codes.

Values MUST conform to the following ABNF.

  # List must be sorted in ascending lexicographic order
  # List must not contain duplicates
  R_VALUE       = [R_ITEM *(',' R_ITEM)]
  R_ITEM        = SPECIAL_GROUP / COUNTRY
  SPECIAL_GROUP = 1*(UPPER_ALPHA / SP)
  # COUNTRY, UPPER_ALPHA are defined as under `p`

References

Normative References

BCP 14: Best Current Practice 14
CABE-ARCH: CABE Architecture Specification
Combined Communications-Electronics Board, “Data-Centric Interoperability Concepts and Design Requirements,” ACP 240(A), May 8, 2025.
NATO Standardization Office, “Confidentiality Metadata Label Syntax,” ADatp-4774, Ed. A, Ver. 1, Dec. 20, 2017.

Colophon

Author
Hugo Landau

NATO ACP240 Attribute Mapping