Species level is the lowest hierarchical level. It represents the Sum composition, i.e., sum of carbon atoms, DBE and number of additional oxygen atoms, e.g. FA 18:1;O. Assumptions by “biological intelligence” need to be stated. Of note, for Sterols the ABCD ring system is assumed and not expressed as DBE.
Molecular species level annotates Lipid species with identified fatty acyl/alkyl residues, e.g. TG 16:0_18:1_18:1, a triglyceride.
sn-Position level annotates GL and GP molecular species: Fatty acyl/alkyl constituents at the glycerol backbone are indicated by a slash, e.g. TG 16:0/18:1/18:1.
DB/DBE-position level annotates species having constituents with Defined position of double bond(s)/double bond equivalent(s), e.g. FA 18:2(9,12);O.
Phosphate-position level annotates Positions of phosphate group(s), e.g. for phosphatidylinositolphosphates PIP[3’] or PIP2[4’,5’].
Structure defined level annotates Molecular species with constituents and functional groups, the latter include Triple bonds (Y), e.g. FA 18:2;OH or FA 18:0;Y.
Full structure level annotates Molecular species with constituents and functional groups including positions, e.g. FA 18:2(9Z,11E);13OH or FA 18:0;9Y.
Complete structure level annotates Molecular species with constituents and functional groups including positions and stereochemistry (acc. to LMSD), e.g. FA 18:2(9Z,11E);13OH[S] (= common name 13S-HODE).