Plotted in black are the line profiles observed by Isella et al. (2007) for the ¹²CO J = 3–2 (upper panel), ¹²CO J = 2–1 (middle panel) and ¹³CO J = 1–0 (lower panel) transitions, with the corresponding profiles from the preferred disc model in red. This refers to a single simultaneous fit to the observed continuum and line data (Col. 3 in Table 6). Observed profiles are obtained by integrating over the whole disc.