[beta-D-GlcpA-(1->3)-alpha-L-GalpA-(1->2)-alpha-D-Rhap-(1->4)-[beta-D-GlcpA-(1->3)-alpha-L-GalpA-(1->2)]-alpha-D-Rhap-(1->4)-beta-D-GlcpA-(1->3)-alpha-L-GalpA-(1->2)]-?-D-Rhap(1->