[mrsD]

I sometimes link to other threads here. I just did that on PN, concerning the
post on PD (which is just excellent BTW).

So I looked it up..and Wikipedia has a discussion of this. (Is there anything that is NOT on Wikipedia these days? LOL)

http://en.wikipedia.org/wiki/Crossposting

Crossposting
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Crossposting is the act of posting the same message to multiple forums, mailing lists, or newsgroups. This is distinct from 'multiposting' which involves posting multiple messages, each posted to a single forum, newsgroup, or topic area. Excessive crossposting is considered bad form because it multiplies traffic without adding any new content. In the extreme case, if all messages were crossposted to every group, then every group would look exactly the same. A crossposter can minimize this problem by specifying that all responses be directed to a single group.

Crossposting can be helpful if the message is of interest to a larger audience. However, crossposting to groups that are irrelevant to the message posted could be considered spamming.

I have bolded what I think is an important point for here. The article goes on in detail as well.