In order to designate R and S from Fisher projections, it is best to build a molecular model and then assign the absolute configuration. Another convention that we use in Fisher projections is to desc...In order to designate R and S from Fisher projections, it is best to build a molecular model and then assign the absolute configuration. Another convention that we use in Fisher projections is to describe the relative configuration of the respective groups with the designations erythro and threo. When two groups are on the same side of a Fisher projection, we say they are erythro; when the groups are on opposite sides, we say they are threo.
