The file name is a positive integer. Other files containing metadata or
arbitrary names can exist in a folder; while the preference is that non-message
files begin with \*(lq.\*(rq, all files that are not positive integers
-.B must
+.I must
be ignored by an
.BR MH \-compatible
implementation. However, implementations are free to indicate to the user
.B mhpath
.IR new ).
New messages are
-.B only
+.I only
permitted to be added to a folder at the end of the message number range.
.PP
To add a new message to a folder, the recommended sequence is: