As stated in the Winbugs manual (
http://www.mrc-bsu.cam.ac.uk/bugs/winbugs/manual14.pdf) data can be entered in S-plus format or in rectangular format. Rectangular format has the form:
Y[] x[]
5 4.1
3 2.1
4 3.5
END
S-plus format (as an example):
list(Y=c(5,3,4),x=c(4.1,2.1,3.5))