As previously answered, the (CPhT-Adv) is indeed a new designation to validate a CPhT's distinction as an experienced pharmacy technician, by way of additional examinations that are relevant to what some seasoned technicians are being allowed to do in some states today. Information can be found here:
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I am interested in the Advanced CPhT courses but it looks as though there is a prerequisite of having experience in each ... and do not have extensive experience.