APP-NAME field of the Syslog message as defined in RFC 5424 - The syslog Protocol.
The APP-NAME field SHOULD identify the device or application that
originated the message. It is a string without further semantics.
It is intended for filtering messages on a relay or collector.
The NILVALUE MAY be used when the syslog application has no idea of
its APP-NAME or cannot provide that information. It may be that a
device is unable to provide that information either because of a
local policy decision, or because the information is not available,
or not applicable, on the device.
This field MAY be operator-assigned.