Effect on the emitting region of the C₂H₂ at 13.71 µm line due to different chemical networks and the rate databases. The left and right axes depict the maximum radial and vertical extent of the emitting region. x15, x85, z15(r) and z85(r) denote the radii and heights at which 15 and 85% of the line flux have originated, respectively. Min z85 and max z15 indicate the maximum vertical extent (z/r) of the region. The gray background is used to highlight the models using the UMIST2012 database, while the white background pertains to models using the KIDA2014 database.