[R] p-value and significance code

[Paul Suckling]

Dear R list members.

Is there anyone out there that might be able to explain the difference
between p-values and significance codes for terms in a linear
regression model (as given by summary.lm for example) for me please?

Do they both give the probability that the observed variation in the
dependent variable due to a given term (or all terms, depending how
they are used) in the model could have been obtained by chance for
example?

I am confused because I have an article which refers to p-values for
individual terms in a linear regression model. They happen to use the
same star syntax when referring to p-values as R's summary.lm command
does for significance codes. R's summary command only gives one
p-value for the whole model though. I have tried searching for help on
"significance code" in the R docs and this list to see what it is
actually being calculated, but to no avail.

Thanks,

Paul