type conversion

[Steven D'Aprano]

On Fri, 02 Jan 2009 15:49:25 -0800, Hamish McKenzie wrote:

> I actually have no idea what ur talking about...  aren't conversations
> threaded by subject?

Not usually. When you hit Reply to a post, your post gets a hidden header 
line that says "I'm a reply to post #12345" (whatever post number it is). 
Just because you change the subject line doesn't change that.

Most newsreader programs thread by that header, not the subject. 
Consequently most people who view posts in thread order will see:


Subject X Y Z
+-- Re: Subject X Y Z
+-- Re: Subject X Y Z
    +-- Re: Subject X Y Z
+-- Re: Subject X Y Z
    +-- Hello I'm changing the subject line
        +-- Re: Hello I'm changing the subject line
    +-- Re: Subject X Y Z
+-- Re: Subject X Y Z

This has the serious disadvantages that:

(1) It annoys people who do threading; and
(2) If people are ignoring a thread, they won't even see your post even 
though you have changed the subject line.

It is considered rude to hijack a thread for a completely new subject, 
although it is acceptable to change the subject line if the thread 
gradually evolves to a new discussion:

Subject X Y Z
+-- Re: Subject X Y Z
    +-- Re: Subject X Y Z
        +-- Subject A B C [was Re: Subject X Y Z]
            +-- Re: Subject A B C [was Re: Subject X Y Z]



Don't mistake the above for off-topic posting, which is something 
completely different, nor for cross-posting, which is different again. 
Off-topic posts are ones that don't have anything to do with the news 
group they are sent to, e.g. a message about Ruby sent to a Python list. 
It is barely acceptable to occasionally post brief off-topic messages 
that are particularly amusing or important if you label them such with 
[OT] or [off-topic] in the subject line.

Cross-posting is sending a single message to more than one newsgroup. If 
you absolutely must cross-post, you should always set the Followup-To 
header to *one* newsgroup. If you don't know how to set followups, then 
don't cross-post.


-- 
Steven