Check your court's website to see if there's a glossary of terms and abbreviations, like the one linked below, or contact your court's clerk.
Disclaimer: I'm only licensed in CA. Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
You don't identify the abbreviations to which you refer, or the court, but it sounds like municipal court. You can contact a court clerk to find out this information, or one of the the King County Law Libraries, located at the courthouses in Seattle or the RJC in Kent. You can look up locations and phone numbers online at kingcounty.gov.