When a campaign keyword not set

Thanks for Piwik,

When I not set the campaign keyword, Piwik server got keyword, sometime referrer hostname, sometime keyword (but, i don’t know where came from), sometime empty.
so, i don’t know why it’s came from various way?

By the way, I want to get empty keyword, if I not set campaign keyword.

any idea?

thank you for your help…

Old thread, but just in case someone else runs into this:

It seems that, if the keyword parameter isn’t set, Matomo attempts to derive it from the referrer. If it can’t detect a keyword in the referrer, it inserts the referrer hostname.

I didn’t see this in the documentation, but I did find the issue where this feature was recommended. https://github.com/matomo-org/matomo/issues/517