Splunk Enterprise Security: What does the error tag mean?

[danielbb]

We see many events tagged as error.
What does it mean?
index=bluecoat has quite a bit of them, for example.

[sumanssah]

@danielbb , please share more details or error screenshot.

[danielbb]

Really interesting, messages such as Sent a DHCP NAK message to client or Sent a DHCP ACK message assigning IP address. Tiny messages and weird that they are assigned the error tag...