seasonal data

[Ruth Cerezo Mota]

Dear all,

I have 100 year data set, but I only have June-Jul-Sep of every year. How
can I 'told' this to grads, I mean, I can open the file without problems and
then  if I ask the first time it says: jun 1860, 3th time: sept 1860, but if
I ask the 4th time instead of says jun 1870 it says: oct 1860 and so on...
Actually the main problem is that I want to create some time series and of
course that in the way that grads is reading the time the xlabel in my
graphics are totally wrong.
Does anybody knows how to read properly the time or modify the labels in a
time serie plot???
thanks a lot
cheers,
Ruth Cerezo-Mota