saves the current document using its default file name.
If the current document is unnamed, the file requester will open and you
will be prompted to select a file. (You can inhibit the file requester opening by
NoFileReq command; see NoFileReq.)
If you escape from the file requester, you can input the file name on the command line.
If the file has been modified since the current document was loaded or last
saved (perhaps by another user),
ne will warn you before overwriting
the updated file.