Different parameters of the model of the molecular envelope of NGC 7027 against the distance to the central star, for the equatorial (thick green line) and polar (dotted-dashed blue line) directions, and the polar blobs (dotted red line). The error bars have been drawn at the center of each shell for the blobs and polar direction only (the errors in the equatorial direction are the same as in the polar direction). Note: the velocity (and its error bars) of the polar blobs has been divided by 5 for displaying purposes.