Conjunction Data Message

Conformance Statement for pkg/cdm, CCSDS 508.0-B-1

CCSDS 508.0-B-1 annex A ships an Implementation Conformance Statement. What follows fills in its shape for both forms: the key-value notation of section 3 and the XML form of section 4.

A1 IDENTIFICATION

A2 REQUIREMENTS

Structure

Header, table 3-1

Relative metadata and data, table 3-2

Object metadata, table 3-3

Object data, tables 3-4 to 3-8

A3 EXCEPTIONS AND UNSUPPORTED FEATURES

No conjunction analysis. Nothing propagates either object, recomputes the miss distance or relative velocity from the two state vectors, or calculates a collision probability. Every one of those is the originator's work, reported in the message. A library that recomputed them would be substituting its own force models for the originator's, which is the opposite of what a warning is for.

Keyword order is not enforced on read. Clause 6.3.1.9 fixes the order. This package accepts the keywords of a section in any order and writes them in the order it read them, so a decoded message re-encodes in the standard's order and a hand-built one comes out in the order its fields were appended. Refusing an out-of-order file would refuse messages that are otherwise unambiguous, and the section boundaries — which do carry meaning — are enforced.

The covariance is not checked for positive definiteness. A message whose matrix is not a valid covariance is structurally valid and is read without complaint. Whether it is usable is a question for whatever computes a probability from it.

Registry values are not checked. ORIGINATOR points at the SANA organizations registry filtered to the Conjunction Data Message Originator role, and CATALOG_NAME at the SANA CATALOG_NAME registry. Neither is validated: checking would mean shipping a copy of a registry that changes without this package.

Enumerated values are not enforced beyond OBJECT. MANEUVERABLE, COVARIANCE_METHOD, OBJECT_TYPE, SCREEN_VOLUME_SHAPE and the rest have normative value sets. They are carried as written. Maneuverable reports YES as true and anything else as false, and reports separately whether the keyword was present at all, so N/A is distinguishable from absent.

A4 IMPLEMENTATION LIMITS

Wire test vectors

The files backing this statement live in the vector corpus — 1 decode vector and 1 corpus file.

Both are published text rather than derived values: clause 3.6.2 prints the example.

One transcription change is recorded in the vector's note. The Blue Book renders its minus signs as U+2212 and the corpus file uses ASCII hyphen-minus, because clause 6.3.1 allows only printable ASCII — the typography in the PDF is a rendering artefact rather than what a real file holds.

The vector asserts the conjunction, the identity of each object, whether each can manoeuvre, and how many rows of covariance each carried. That last one matters because it is not recoverable from the numbers: an absent row and a row of zeroes are identical in the matrix. The floats are checked in pkg/cdm against the same text.

See CONTRACT.md for how to consume these, and how this is verified for what rests on a published vector versus a reading of the clause.