There are still some people posting files using the split tool. This results in a file being broken up in to equal-size parts with a number appended on the end. For example, file.rar.001, file.rar.002, etc. It doesn't look like Usenapp is correctly detecting this because each one of those will be a separate line in the newsgroup window instead of grouped together. So you'd have to download each one individually and then post-process it. There's nothing special about these files. They can be concatenated together in order. There's no metadata in each split file.