Definition of new regions for the selection of symbiotic stars in the IPHAS (upper panel) and 2MASS (lower panel) colour−colour diagrams. Circles and squares indicate the location of the S and D-type systems, respectively, discovered so far by the IPHAS survey. The location of the unreddened main-sequence (MS), giants sequence (G), and the reddening vector for A_V = 3 mag (arrow), are also shown (see Paper I and Drew et al. 2005 for more details).