mangos/mangos — comment on commit 69c1fe555acab09594cc2709fe077b05874d8ed0
File: sql/updates/11926_01_mangos_creature_template.sql line 3
By faramir118:

It's a bitmask

1 = allow ground
2 = allow swimming
4 = allow flying

| them together to allow multiple inhabit types
1 | 2 = 3 = allow ground and swimming
3 | 4 = 7 = allow ground and swimming and flying