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Top-level Field Length/Type Conformance

This MISB ST 0902 structural rule checks that MISMMS Table 1 top-level items are encoded using the lengths and data types required by the standard.

What This Test Does​

For each decoded claimed MISMMS packet, the rule validates the top-level items defined in MISB ST 0902 Table 1 against their required encoding form.

Examples include:

  • Tag 1 Checksum as 2 bytes
  • Tag 2 Precision Time Stamp as 8 bytes
  • Tag 65 UAS Local Set Version as 1 byte
  • Tag 94 Motion Imagery Core Identifier as a valid MISB ST 1204 core identifier no longer than 50 bytes
  • fixed-width numeric items using their Table 1 byte length
  • top-level nested items such as Tag 48 using the expected nested local-set decoder

✅ Pass Criteria​

The test passes when every present top-level MISMMS item conforms to the MISB ST 0902 Table 1 length and type requirements.

❌ Fail Criteria​

The test fails when a top-level MISMMS item is encoded with the wrong byte length, the wrong top-level type, invalid ISO 646 content where applicable, or invalid nested content for items such as Tag 48 or Tag 94.

Notes​

This rule is intentionally stricter than generic MISB ST 0601 decoding because it enforces the MISB ST 0902 MISMMS profile, not just ST 0601 packet parseability.