[4)-alpha-L-Rhap-(1->3)-alpha-D-Galp-(1->2)-alpha-D-Manp-(1->]n
[4)-alpha-l-rhap-(1->3)-alpha-d-galp-(1->2)-alpha-d-manp-(1->]n
A polysaccharide composed of a backbone of linear trisaccharide repeating units consisting of α-<small>L</small>-rhamnose, α-<small>D</small>-galactose and α-<small>D</small>-mannose residues linked sequentially (1→3) and (1→2), the repeating units being joined to each other via α(1→2)-linkages; corresponds to the backbone of the O-antigen repeat unit of the O:12 antigen common to <em>Salmonella</em> serogroups A, B and D.