wake vortex category seems to be invalid

[wrobell]

In the book

1. tc=-2, category=1; Surface emergency vehicle
2. tc=2, category=3; Surface service vehicle <- should be category 2
3. tc=2, category=4–7; Ground obstruction <- ground obstruction is category 3; categories 4-7 are reserved

In ICAO doc 9871, 2nd edition, table A-2-8, p. A-31

1. tc=2, category=1: surface emergency vehicle
2. tc=2, category=2: surface service vehicle
3. tc=2, category=3: ground obstruction
4. tc=2, category=4-7: reserved