| Feature | source |
| Definition | identifies the biological source of the specified span of the sequence; this key is mandatory; more than one source key per sequence is allowed; every entry/record will have, as a minimum, either a single source key spanning the entire sequence or multiple source keys, which together, span the entire sequence |
| Mandatory Qualifiers |
/organism="free text" /mol_type=One chosen from the following:
|
| Optional Qualifiers |
/cell_line="free text" /cell_type="free text" /chromosome="free text" /clone="free text" /clone_lib="free text" /collected_by="free text" /collection_date="DD-Mmm-YYYY", "Mmm-YYYY" or "YYYY" /country="<country_value>" where <country_value> is any value from the controlled vocabulary in paragraph 10 of this Annex /cultivar="free text" /dev_stage="free text" /ecotype="free text" /environmental_sample /focus /frequency="free text representing the proportion of a population carrying the feature expressed as a fraction" /germline /haplogroup="free text" /haplotype="free text" /host="free text" /identified_by="free text" /isolate="free text" /isolation_source="free text" /lab_host="free text" /lat_lon="free text" - degrees latitude and longitude in format "d[d.dddd] N|S d[dd.dddd] W|E" /macronuclear /map="free text" /mating_type="free text" /note="free text" /organelle=One of the following controlled vocabulary terms and phrases:
/plasmid="free text" /pop_variant="free text" /proviral /rearranged /segment="free text" /serotype="free text" /serovar="free text" /sex="free text" /strain="free text" /sub_clone="free text" /sub_species="free text" /sub_strain="free text" /tissue_lib="free text" /tissue_type="free text" /transgenic /variety="free text" |
| Molecule Scope | any |
| Comment | transgenic sequences must have at least two source feature keys; in a transgenic sequence the source feature key describing the organism that is the recipient of the DNA must span the entire sequence. |