Skydiving equipment must be certified for use in a country however there are some international standards which equipment can be certified by. This shows the equipment has passed the required tests to meet the certification. A certification being granted does not mean the equipment is immune from manufacturing errors nor does the absence of a certification mean it is dangerous. You can speak with a Rigger if you have any questions about how your equipment is built.
Many thanks to Tom Hill for writing this article and for taking the pics.
Technical Standard Order C23 (TSO C23)
This is likely in the context ‘Fully certified under TSO C23’ or ‘Fully TSO’ed’. Technical Standard Order C23 is a Federal Aviation Authority standard that skydiving Harnesses, Containers and Reserves must meet in order to be sold in the United States. Not all equipment is certified to TSO C23. If your equipment is not certified to TSO C23, you can jump it in the United States for personal use only. In addition, some skydiving federations will not allow you to jump non TSO C23 certified equipment beyond a certain timeframe from arrival for example 3 months. In any case, the foreign federation will require the equipment you jump to be certified in your home nation. Make sure you check the requirements with the country you are visiting. The letter after the TSO is a subsection, for example TSO C23 (d).
Removal of any TSO label will void the certification so ensure it is intact and present.
Figure 6: An example of a TSO C23 on a Skydiving Container (Left). The TSO label may be in other places. If this label is present on the Container, the Harness and Container information may be behind it. Others have the TSO C23 label in the Reserve Pin Cover Flap (right).