Kokua has a new version of their viewer out. This version changes from RLVa to RLV. So, what does that mean? Basically, just that you need to do a clean install. The RLVa settings need to be removed and the RLV settings installed. Installing over the previous version won’t clear the RLVa settings, thus the clean install is needed.
RLVa and RLV are similar. Both add to the viewer the ability to have in-world Linden Scripting Language (LSL) scripts control the viewer. To some lesser extent the new Linden Experience Tools serve a similar purpose.
The RLV/RLVa feature is often used for making adult toys. One of the uses that reveals what RLV/RLVa can do is adding or removing clothes. This can only happen in a viewer with RLV/RLVa enabled. But, this does not have to be limited to adult toys or activities. If all viewers have a similar feature then merchants can use the ability to provide demo clothes. Long ago this was a rod Humble idea. Experience Tools is the Linden step on that path.
The RLV API was/is made by Marine Kelly. The API (Application Programming Interface) provides a way for a script to talk to the viewer and tell it what to do. The RLVa is a similar system, but shares no RLV code. Different ways of doing the same thing.
The Kokua peeps feel RLV by Kelly is kept more up-to-date with the Linden’s SL Viewer. I don’t know. But, that is the stated reason for the change.
Kokua now has the Snowstorm Fall Updates, GPU Benchmark fixes, the SL 3.7.23 Maintenance fixes, and the pipeline fixes. This makes Kokua one of the more up-to-date third party viewers out there.
NOTE: If you are using this viewer on OpenSim grids there is a fix in the comments on the announcement page that you need to implement. See: Kokua 3.7.24.