"Write current buffer into file FILENAME.
This makes the buffer visit that file, and marks it as not modified.
-If you specify just a directory name as FILENAME, that means to use
-the default file name but in that directory. You can also yank
-the default file name into the minibuffer to edit it, using \\<minibuffer-local-map>\\[next-history-element].
-
-If the buffer is not already visiting a file, the default file name
-for the output file is the buffer name.
+Interactively, prompt for FILENAME.
+If you specify just a directory name as FILENAME, that means to write
+to a file in that directory. In this case, the base name of the file
+is the same as that of the file visited in the buffer, or the buffer
+name sans leading directories, if any, if the buffer is not already
+visiting a file.
+
+You can also yank the file name into the minibuffer to edit it,
+using \\<minibuffer-local-map>\\[next-history-element].
If optional second arg CONFIRM is non-nil, this function
asks for confirmation before overwriting an existing file.