If you are referring to the Clerk of Court's website court docket, it is just the Clerk's notation that one of the parties filed a document titled "Acknowledgement of Additional Tangible Evidence". It could be a supplemental witness list, a list of new police or lab reports which were sent to the defense, or some sort of document to be used as evidence in the case. The evidence or documents themselves do not have to be filed with the Clerk, just the Notice or Acknowledgement which state that the additional evidence has been sent to the other party on a particular date.
Legal disclaimer: this response is not intended to create any attorney-client relationship and is based on the limited facts given and should not be relied on as legal advice. It is recommended that you consult with an attorney before taking any action based on the foregoing statements.
The best way to find out is to ask the Clerk next time you are in court.
What kind of case do you have? Are you represented by a lawyer? Has the prosecution given you notice of supplemental discovery?
Let me know if you need help with this.
Silber Criminal Law Firm