| OML | orbitomental line |
|---|---|
| OSCAR | on-line survey, certification and reporting system |
| PAL | pathology laboratory; peptidyl-alpha-hydroxyglycine alpha-amidating lysine phase alteration plane; p... |
| PcB | near point of convergence to the intercentral base line [punctum convergens basalis] |
| PLES | parallel-line equal space |