Based on new calculations we reconfirm the low and high density limits on the forbidden fine structure line ratio [ O ii ] I ( 3729 ) / I ( 3726 ) : \lim _ { N _ { e } \to 0 } = 1.5 and \lim _ { N _ { e } \to \infty } = 0.35 .
Employing [ O ii ] collision strengths calculated using the Breit-Pauli R-matrix method we rule out any significant deviation due to relativistic effects from these canonical values .
The present results are in substantial agreement with older calculations by Pradhan ( 1976 ) and validate the extensive observational analysis of gaseous nebulae by Copetti and Writzel ( 2002 ) and Wang et al . ( 2004 ) that reach the same conclusions .
The present theoretical results and the recent observational analyses differ significantly from the calculations by MacLaughlin and Bell ( 1998 ) and Keenan et al . ( 1999 ) .
The new maxwellian averaged effective collision strengths are presented for the 10 transitions among the first 5 levels to enable computations of [ O ii ] line ratios .