ISO 5775-2:2015 specifies rim dimensions for bicycle tyres: it gives only those rim contour dimensions necessary for tyre mounting and to fit the tyre on the rim.
ISO 5775-1 covers designations and dimensions for tyres.
ISO 5775-2 covers straight side (SS) rims, hooked bead type (HB) rims and crotchet type (C) rims.