plotting query

[susan@stats.ucl.ac.uk]

Dear Colleagues

I am having difficulty getting S to plot the correct ticks/intervals using
 "xaxp" in plot. I would like ticks every 4 units.

My plots are something like

par(mfrow=c(3,1))

plot1<-plot(x1,y1,  .... xlim=c(-10,40),.. xaxp=c(-8,48,14) ....)
plot2<- same as 1 but y2
plot3<- same as 1 but y3

I cannot chnage the x-axis from ticks at -10 and at intervals of 10 or 5
thereafter.

I am using splus2000 for windows

Many thanks
Susan