Piwik tracker uses the get method “?action_name =” to report the page title to Piwik server.
We have different character codes, but no regard is given to these character codes and presuppose use UTF-8, by the look of source codes.
That’s correct or not ? If that’s correct, where these function is written in the piwik.js ?
Thank you for attention.
Hi Piwik Japan 
Piwik expects UTF-8 data.
However you can also input the data in another character set using “cs” parameter. Doc: http://developer.piwik.org/api-reference/tracking-api
‘cs’ — The charset of the page being tracked. Specify the charset if the data you send to Piwik is encoded in a different character set than the default utf-8.
Currently, looking at the code, this parameter will only be used for the Query String of the URL being tracked.
if you want to send action_name in a new charset, this would require a new feature in Piwik. Please create feature request: https://github.com/piwik/piwik/issues
Thank you. And I solved the problem When pk_campaign = (utm_campaign =) is used, which is utf-8, string will cut 70 "bytes" without boundary. · Issue #9257 · matomo-org/piwik · GitHub. But another problem remains. I will show it.