The /experiment qualifier provides a description of the nature of the experimental evidence that supports the identification of the feature annotated.
Publications in printed form as well as online can be used to support the underlying experiment by using the corresponding PMID or digital object identifier (DOI).
/experiment="Northern blot [DOI: 12.3456/FT.789.1.234-567.2010]"
/experiment="heterologous expression system of Xenopus laevis oocytes [PMID: 12345678, 10101010, 987654]"
Furthermore, ontology terms and database identifiers such as SRA, Geo, ECO, Pride but in principal any database accessions can be used to indicate a sample identifier.