Seems to be some confusion on how the trunk and hatch locks interact with the central locking system. The diagrams below are from UrS4 sedan, UrS6 Sedan and Avant Owner's manuals.
My 93 S4 sedan 94 S4 V8 avant are a bit different: The 93 UrS4 sedan with remote central locking is similar to the diagram below but to open more than just the trunk, I need to turn the key twice from Position "a" to "b" in rapid succession; turning once and holding does nothing. However, the info about Postion "c" and "d" is correct. In contrast, the 94 UrS4 avant does NOT have remote central lock so there is no position "c", just "a", "b" and "d", as per the diagram.
My 98 C4 A6 avant was different again (not sure why). It was shifted by 90 degrees: vertical = central locking control; horizontal = locked/valet mode.
My 93 S4 sedan 94 S4 V8 avant are a bit different: The 93 UrS4 sedan with remote central locking is similar to the diagram below but to open more than just the trunk, I need to turn the key twice from Position "a" to "b" in rapid succession; turning once and holding does nothing. However, the info about Postion "c" and "d" is correct. In contrast, the 94 UrS4 avant does NOT have remote central lock so there is no position "c", just "a", "b" and "d", as per the diagram.
My 98 C4 A6 avant was different again (not sure why). It was shifted by 90 degrees: vertical = central locking control; horizontal = locked/valet mode.