/etc/acpi/events/sony-volume-down is in acpi-support 0.142-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | # /etc/acpi/events/sony-volume-down
event=sony/hotkey (SPIC|SNC) 00000001 0000000e
action=/etc/acpi/voldownbtn.sh
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