time_counter as axis

["Arthur M. Greene" <amg13@xxxxxxxxxxxxx>]

Hello Ferreters...

I have 5 years of monthly data at a single gridpoint, with the time axis
specified by a simple index: 1,2,3,4,5... 60, rather than by specific
dates. According to the "show axis" command, this is a "time_counter,"
and ferret shows "# pts" as "60 r," beginning at 1 and ending at 60. I
would like to display a monthly climatology, but only for the last four
(or possibly three) years. 

Let's call the variable in question v. Then, when I do

let vclim = v[GT=month_reg@asn]
plot vclim

I get a nice climatological plot, with Jan Feb Mar... along the x-axis
(these happen to be the correct months, even though I haven't told
ferret how to map the time index to the calendar.)

However, if I pick off the last four years,

let v1 = v[T=13:60]
let v1clim = v1[GT=month_reg@asn]
plot v1clim

the resulting plot is blank; a listing shows empty values.

I have read a lot of the grid and axis parts of the docs, but I'm afraid
it is still not clear to me (a) how to produce such a delimited-interval
climatology, and (b) what the problem actually is with the formulation
as given above.

Comments appreciated, and thanks!

A. Greene