What's the difference bewteen these PC hardware newsgroups:
alt.comp.hardware
alt.comp.hardware.pc-homebuilt
alt.comp.hardware.homebuilt
and even:
uk.comp.homebuilt
I get tempted to crosspost questions because I don't know how one
these group's readership is different from another.
But ... I don't want to upset people whose newsreader doesn't
suppress posts they've already read in another group.
You should try to find the charter for a group if you are not sure
what the purpose of a particular group is. Most groups have one,
although in the case of alt.* groups it may be somewhat informal
or only a single line description carried by your news server. If
you consult the charters you will find that alt.comp.hardware.pc-homebuilt
is the only _PC_ group that you have listed.
In general is it considered bad form to cross post between local
and regional and global newsgroups for two reasons. Firstly local
groups have far more implicit context - if you post to uk.comp.homebuilt
it is assumed that you are UK based, whereas this needs stating
explicitly on other groups, and turns of phrase or referencing e.g.
TV programmes may be appropriate on a local group but not elsewhere.
Bear in mind this affects not just you, but anyone that responds
to your posts.
Secondly, if a message includes local groups then respondents not
in that locality are probably using a server that does not carry
the local groups. This can cause all sorts of problems if it isn't
noticed before the post is attempted - depending on the reader the
message may be unsubmittable until the missing groups are removed
from the Newgroups: header, with no indication as to which of the
groups are causing the problem.
As to cross posting more generally, most newsreaders keep track of
posts by message-id and will only show the messages as unread (or
at all) in the first group you encounter and read them. This is
the source of all those flames about multi-posting (posting an
identical message to different groups) instead of cross posting
(posting the same only once, but to multiple groups), since
multi-posting breaks this behaviour.