/usr/share/mimelnk/application/x-pcb-layout.desktop is in pcb-common 20140316-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 | [Desktop Entry]
Encoding=UTF-8
Comment=PCB layout
Comment[nl]=PCB opmaak
Comment[pt_BR]=Traçado PCB
Comment[ru]=PCB трассировка
MimeType=application/x-pcb-layout
Type=MimeType
Icon=application-x-pcb-layout
Patterns=*.pcb
X-KDE-IsAlso=text/plain
|