A spreadsheet cell containing a product name, sequence, amount and supplier note may be understandable to its author but difficult for software to interpret. Machine-readable metadata separates those concepts and defines what each field means.
Define the information before choosing the format
Begin with the decisions the receiving system must make. Does it need to match a molecular entity, identify a purchased lot, locate a certificate or calculate an amount? These tasks require different fields and should not depend on parsing one display name.
Separate a molecular description from a commercial product record and from a physical sample record. Several products may claim the same molecule, while several containers may share one lot. Collapsing these relationships creates false equivalence.
Write a small data dictionary explaining each field, allowed values and evidence requirements. Specify whether an amount is nominal, measured or calculated and what object it refers to.
Choose a format that preserves these meanings during export and import. A valid file is only the beginning: a receiver can parse every character and still misunderstand the scientific content.
Preserve the chemical description
The HELM project explains that its representation depends on monomer definitions and that curation of the monomer set is critical. Its documentation describes a core library developed with EBI and PubChem and guidance for naming additional monomers.Pistoia Alliance HELM — Monomers (opens in a new tab)
For a laboratory exchange record, this illustrates why an unfamiliar residue abbreviation needs a defined meaning. A local nickname may be convenient inside one team yet ambiguous when the file moves to another system.
Where a recognised notation is adopted, record the notation version and relevant reference library. Validate against that specification rather than assuming that a plausible-looking string is conformant.
Keep values, units and evidence separate
| Field group | Information to preserve |
|---|---|
| Molecular description | Sequence or structure, termini, modifications and their positions |
| Description provenance | Declared, measured or inferred; source identifier and location |
| Commercial identity | Supplier and catalogue identifier |
| Physical material | Lot and container identifiers |
| Quantity | Numerical value, unit, basis and nominal/measured status |
| Missing information | Explicit unknown value with a reason where useful |
Do not use zero to represent an unknown amount. Zero is a quantitative statement. Similarly, an empty modification field needs a defined interpretation: it might mean no modification is declared, or it might mean the information was not supplied.
Keep the source wording available alongside the normalised field when interpretation was required. If a document says only “project reference”, the exported record should not silently turn that phrase into a fully resolved molecular identity.
Identifiers that look numeric may still be text. Leading zeros, punctuation and case can matter in catalogue or lot references, so test that spreadsheet software does not alter them automatically.
Check the round trip
Export a small set of representative records and import them into the receiving system. Include a modified peptide, a mixture, an unknown field and multiple containers from one lot so that the test covers meaningful distinctions.
Compare the interpreted records, not merely the row count. Confirm that units remain attached to values, evidence links still resolve and unknown information has not acquired a default value.
Record transformations such as unit conversion or identifier normalisation. A future user should be able to explain why the received value differs in presentation from the source document.
Useful metadata makes both known information and its limits portable. It should reduce repeated interpretation work while leaving a clear path back to the evidence behind the structured fields.
Sources and further detail
- Pistoia Alliance HELM — Monomers (opens in a new tab)
Official project documentation inspected for monomer-definition and library-curation requirements. The local field map is original and is not claimed to implement HELM.
Sources checked 20 September 2026. Reporting examples are illustrative unless explicitly identified as supplied-document transcriptions. This article has not undergone independent scientific peer review.