.SS "Sequence Negation"
.B Nmh
-provides the ability to select all messages not elements of a
-user-defined sequence. To do this, the user should define the entry
+provides the ability to select all messages
+.B not
+elements of a user-defined sequence.
+A special string is used to preface an existing user-defined
+sequence name. This specification then refers to those
+messages not elements of the specified sequence name.
+The default negation prefix is the exlamation mark `!',
+but it may be change to any string, by defining the entry
\*(lqSequence\-Negation\*(rq in the
.B nmh
-profile file; its value
-may be any string. This string is then used to preface an existing
-user-defined sequence name. This specification then refers to those
-messages not elements of the specified sequence name. For example, if
-the profile entry is:
+profile file.
+For example, if the profile entry is:
.PP
.RS 5
Sequence\-Negation: not
.PP
Obviously, the user should beware of defining sequences with names that
begin with the value of the \*(lqSequence\-Negation\*(rq profile entry.
+The default value `!' was chosen due to its similar meaning in the C
+programming language, and because it cannot be part of a user-defined
+sequence. But if your shell provides history expansion,
+you might need to quote the exlamation mark (prefix it with a backslash).
+.PP
+To deactivate the negation mechanism, define Sequence\-Negation in your
+profile to an empty value.
.SS "The Previous Sequence"
.B Nmh
file.
.SS "The Unseen Sequence"
-Finally, many users like to indicate which messages have not been
-previously seen by them. The commands
+Finally, the unseen sequence indicates which messages have not been
+previously seen by the user.
+The commands
.BR inc ,
.BR rcvstore ,
.BR show ,
.BR mhshow ,
and
.B flist
-honor the profile entry
-\*(lqUnseen\-Sequence\*(rq to support this activity. This entry
-in the
-.I .mmh/profile
-should be defined as one or more sequence
-names separated by spaces. If there is a value for
-\*(lqUnseen\-Sequence\*(rq in the profile, then whenever new messages
-are placed in a folder (using
+honor the sequence.
+Whenever new messages are placed in a folder (using
.B inc
or
.BR rcvstore ),
-the new messages will also be added to all the sequences named in this
-profile entry. For example, a profile entry of
-.PP
-.RS 5
-Unseen\-Sequence: unseen
+the new messages will also be added to the unseen sequence.
.RE
.PP
-directs
-.B inc
-to add new messages to the sequence \*(lqunseen\*(rq.
-Unlike the behavior of the \*(lqPrevious\-Sequence\*(rq entry in the
-profile, however, the sequence(s) will
+.BR inc ,
+for example,
+adds new messages to the unseen sequence.
+Unlike the behavior of the previous sequence, however,
+the unseen sequence will
.B not
be zeroed by
.BR inc .
.BR next ,
or
.B prev
-displays a message, that message will be removed from
-any sequences named by the \*(lqUnseen\-Sequence\*(rq entry in the
-profile.
+display a message, that message will be removed from
+the unseen sequence.
+.PP
+The default unseen sequence is named `u'.
+To change, define a \*(lqUnseen\-Sequence\*(rq entry in your profile.
+It may also contain multiple sequence names, separated by spaces.
+In this case, anything that applied to a single unseen sequence,
+applies to multiple ones, too.
+.PP
+The unseen sequence mechanism is automatically activated.
+To deactivate it, define the \*(lqUnseen\-Sequence\*(rq entry
+in your profile with an empty value.
+
.SH FILES
.fc ^ ~