1 INTRODUCTION

2 DATA

3 IDENTIFICATION OF OBA STAR

3.1 The Initial Sample

3.2 Removing stars later than A5

3.3 The sample grouping

4 RADIAL VELOCITY MEASUREMENTS AND ANALYSIS

4.1 RV measurements

4.2 Criterion for binarity

4.3 Observed binary fraction

5 INTRINSIC MULTIPLICITY PROPERTIES

5.1 Monte-Carlo method

5.2 Validation

5.3 Results and Discussion

6 CONCLUSIONS