Guys, it is just a statement by the company that the welder in question has been continually welding using a process that he/she was qualified with....any supervisor or manager could do that whether they were qualified (and documented) as an inspector or not really doesn't have anything to do with it...does it?
I happen to be a CWI and sign off that my welders have been continually welding, but really our plant manager could sign those same documents and he isn't a CWI or qualified in any way, shape or form. There are owners of small companies signing these welder continuity records who are not certified or qualified, but they have been paying their salaries and observing these guys welding for them over the past six months, so they sign and date the document stating just that....may be I'm not following the original question, so I'll stop rambling for now.
***EDIT***
now that I'm re-reading the OP....I was originally thinking they were asking about maintaining the welder's continuity....rather than actually qualifying and testing.....sorry about the off topic ramble.