Theoretical expressions for the local values of six types of unnormalized R-indices are derived for an imperfectly related incomplete model of a crystal (centrosymmetric and non-centrosymmetric) with truncated data which is characterized by a truncation limit yt. These indices depend on the parameters σ1, D and yt. In the situations of practical interest (i.e., σ12>0·3 and yt<0·2) R-indices for the centro-symmetric case decrease as ytincreases while these for the non-centro-symmetric case remain more or less constant.