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17. Narrowing

Narrowing means focusing in on some portion of the buffer, making the rest temporarily inaccessible. The portion which you can still get to is called the accessible part. Canceling the narrowing, which makes the entire buffer once again accessible, is called widening. The amount of narrowing in effect in a buffer at any time is called the buffer's restriction.

Narrowing can make it easier to concentrate on a set of messages by eliminating clutter. It can also be used to restrict the range of operation of a search command or repeating keyboard macro.

C-x n
Narrow down to between point and mark (narrow-to-region).
C-t n expression RET
Narrow to the tagset defined by tag-expression (narrow-to-tagset).
C-x w
Widen to make the entire buffer accessible again (widen).

When you have narrowed down to a part of the buffer, that part appears to be all there is. You can't see the rest, you can't move into it (motion commands won't go outside the accessible part), you can't change it in any way. However, it is not gone, and if you save the folder all the inaccessible messages will be saved. The word `Narrow' appears in the mode line whenever narrowing is in effect.

One narrowing command is C-x n (narrow-to-region). It sets the current buffer's restrictions so that the messages in the region remain accessible but all messages before or after the region are inaccessible. Point and mark do not change.

Another narrowing command is C-t n (narrow-to-tagset). It prompts for a tag expression, and then set the current buffer's restrictions so that the messages in the tagset remain accessible but all the other messages are inaccessible.

The way to cancel narrowing is to widen with C-x w (widen). This makes all the messages in the buffer accessible again.

Narrowing can be very useful if you have a set of messages that you want to deal with independently of any others; such as all the messages from a mailing list, or from a certain user. Use C-t s (search-and-tag) to tag the messages you are interested in, and then use C-t n to narrow the buffer to only the tagged messages. When you are done with the messages, use C-x w to widen to buffer.

Another use for narrowing is when you are using tags to kill messages. You can use C-t n to narrow to the messages you intend to kill, and then conveniently scan the messages to make sure that you are happy to kill them all; using C-t u to untag any messages that you decide you want to keep. Finally you can either kill the tagset with C-t C-k (kill-tagset), or set the mark and point at opposite ends of the buffer and use C-w (kill-region). When you have finished, use C-x w to widen the buffer.

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This document was generated by Malc Arnold on August, 22 2002 using texi2html