1. INTRODUCTION

2. SOURCES

3. OBSERVATIONS

4. DATA REDUCTION
4.1. RFI removal
4.2. Confidence tests

5. RESULTS
5.1. Magnetic Field Derivation
5.2. Linear Polarization

6. DISCUSSION
6.1. Comparison with Galactic OH masers
6.2. Strong Fields and Time Variability
6.3. Dynamical importance

7. CONCLUSIONS