Some articles on busgates:

Vienna International Airport - Terminal - Concourses
... There are gates with jetbridges and busgates) Area C ("pier west") Gates C31–C42 (only jetbridges), C35–C41 transfer gates, C71–C75 (only buses) Several gates are used for ... The busgates C71-C75 serve only Schengen flights ... Area F ("pier south") Gates F01-F37 (jetbridges as well as busgates) Is only serving Schengen flights and is situated on level 1 ...