IMGT®, the international ImMunoGeneTics information system® (http://imgt.cines.fr) provides a common access to expertly annotated data on the genome, proteome, genetics and structure of immunoglobulins (IG), T cell receptors (TR), major histocompatibility complex (MHC) of human and other vertebrates, and related proteins of the immune system (RPI) of any species. RPI include proteins that belong to the immunoglobulin superfamily (IgSF) and MHC superfamily (MhcSF). IMGT has set up a unique numbering system, which takes into account the structural features of the Ig-like and Mhc-like domains. In this paper, we describe the IMGT Scientific chart rules for the description of the IgSF V type and C type and of the MhcSF G type domains. These rules are based on the IMGT-ONTOLOGY concepts and are applicable for the sequence and structure analysis, whatever the species, the IgSF or MhcSF protein, or the chain type. We present examples of IMGT Colliers de Perles of IgSF V type (V-DOMAIN and V-LIKE-DOMAIN), C type (C-DOMAIN and C-LIKE-DOMAIN) and MhcSF G type (G-DOMAIN and G-LIKE-DOMAIN) based on the IMGT unique numbering. These standardized two-dimensional graphical representations are particularly useful for antibody engineering, sequence- structure analysis, visualization and comparison of positions for mutations, polymorphisms and contact analysis.