ViewSonic CDE12 User Manual page 38

Item Description
Custom App
Setup a custom .apk application for Custom input source. If a
Custom App is setup, the display will open the App when the
input source is changed to "Custom".
Source Setting
External Storage
Enable/Disable USB storage.
NOTE:
Re-insert any connected USB external storage
Security
device(s) after enabling.
Unknown Sources
Allow or don't allow the installation of unknown .apk files.
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