The return value from isdSend(), as a result, will be 64 bytes (sizeof isdHeader) larger than usual in the event of successful writev()s. This has not been put into the distribution yet.
Also, the writev() was inserted inside a do{}while; loop checking for EINTR to make sure silly things like interrupts don't cause write errors.
Documentation is coming soon. It was not made part of the isect distribution because it's an example of an independent worker (config and makefiles) that others might be able to use as a template.