| Acronym | Meaning |
| VCC-IOS | Vibrational Close-coupling-(rotational) Infinite-order Sudden (for Inelastic Mol. Collisions Calcns.) |
| OWLS | Optical Waveguide Lightmode Spectroscopy |
| PSD | Prevention Of Significant Deterioration |
| SCLS | Spectral Collocation (by) Least Squares |
| HSPF | Hydrological Simulation Program-Fortran |
| IHSS | International Humic Substances Society |
| PTM | Perturbation Trajectory Method (in Gas-surface Collision Dynamics) |
| MRL | Method Reporting Limit |
| DEMS | Differential Electrochemical Mass Spectrometry |
| PSI | Pollution Standard Index |