Define what must survive
Begin with the intended future use. A visual reference, manufacturing authority model and inspectable product definition have different preservation needs. Identify the required geometry, assembly context, PMI and metadata before selecting an exchange format.
Validate the transfer in context
Keep the native source identity, exporter release and settings with the neutral file. Check geometric observations together with required product information. Matching aggregate properties can support a review but cannot prove that every face, tolerance or association survived.
Retain a reproducible evidence package
Store the original inputs, their identities, the comparison method and the resulting findings. Keep unresolved questions and review decisions with the record. A future reviewer needs to distinguish what was evaluated at the time from what was merely assumed.
Plan a retrieval check
A successful archive write does not demonstrate successful future use. Define how a retrieved model will be opened, checked and compared with its retained evidence. Record any changed interpretation caused by the receiving system or a revised validation method.
Understand the LOTAR boundary
LOTAR addresses long-term archival and retrieval processes; its fundamentals use neutral product data within a wider preservation approach. PartDatum can contribute comparison evidence, but it is not an archive repository or a complete LOTAR implementation. Do not describe a STEP file plus a comparison report as universal archival compliance.