  Two sets of observational carbon stellar yields for low-and-intermediate mass
stars are computed based on planetary nebula abundances derived from C II
lambda 4267 and C III lambda lambda 1906 + 1909 lines, respectively. These
observational yields are assumed in chemical evolution models for the solar
vicinity and the Galactic disk. C/O values observed in stars of the solar
vicinity and Galactic H II regions are compared with those predicted by
chemical evolution models for the Galaxy. I conclude that the C yields derived
from permitted lines are in better agreement with the observational constraints
than those derived from forbidden lines.
