Comparison of the present effective collision strengths with the results from Butler & Zeippen (1989) and Ramsbottom et al. (2001) for the forbidden (a) 3 s ²3 p ^{3  4} S ^o _3/2 → 3 s ²3 p ^{3  2} D ^o _3/2, (b) 3 s ²3 p ^{3  4} S ^o _3/2 → 3 s ²3 p ^{3  2} P ^o _1/2, (c) 3 s ²3 p ^{3  2} D ^o _3/2 → 3 s ²3 p ^{3  2} D ^o _5/2, and (d) 3 s3 p ^{4  4} P _5/2 → 3 s3 p ^{4  2} D _5/2 transitions in Cl iii as a function of electron temperature. Solid curve: present 68- LSJ state calculation; dotted curve: 23- LS state calculation of Ramsbottom et al. (2001); dashed curve: R-matrix calculation of Butler & Zeippen (1989).