ANSI Common Lisp 20 Files 20.1 File System Concepts
20.1.2 File Operations on Open and Closed Streams
Since treatment of open streams by the file system may vary considerably between implementations, however, a closed stream might be the most reliable kind of argument for some of these functions - in particular, those in the next figure. For example, in some file systems, open files are written under temporary names and not renamed until closed and/or are held invisible until closed. In general, any code that is intended to be portable should use such functions carefully.