Full_Name: Kevin Cain Version: 2.2.1 OS: Windows XP Submission from: (NULL) (128.95.124.144) In the following command, R ignores the xaxp command - it places tick marks at 1, 1.5, 2.0, etc regardless of what the third argument is (I want them only at integer values). plot(x=c(min(time),max(time)),y=c(min(y-se),max(y+se)),type='n',xaxp=c(1,4,3), xlab='Measurement Time Point', ylab='Accelerometer Mean VMU/min') A prior bug report says this problem has been fixed (Graphics-fixed/1654), but it looks like that referred to the unix version.