Minecraft wiki entry for Block_update_detector, associated text: 1 What it detects
2 Types of BUD Switches
2.1 In-Game
2.2 Piston Based
2.3 Stuck-Piston Based
2.4 Dropper Based
2.5 Redstone Torch Based
2.6 Redirection based
3 Variations
3.1 BUD in Bedrock Edition
3.2 T-BUD
4 History
5 References