What is meant by a "permanent working paper"?
Without knowing what the paper is, it's hard to tell, but here is a situation where that might make sense:
Many permanent organizations -- say, the National Labs in the United States, NASA, or large research organization in other countries -- have an archive for papers that might not be research-y enough to be published in journals, but are still useful to be kept in a permanent archive. Think articles that provide very specific data about the aerodynamics of a particular wing shape that someone has investigated in the 1960s. Or an evaluation of certain materials to build a nuclear reactor. These are in essence the outcomes of engineering work, not of research, and are often not published in research journals.
These archives go by different names. &quot;Permanent working paper&quot; is one of the names that one could use for this. The point is that they are &quot;working papers&quot; in the sense that someone is &quot;working with the data shown therein&quot;, and they are &quot;permanent&quot; in the sense that this is not work in progress.