Extract and encode the times the first and last observations were taken. Provided only for compatibility with S version 2.
start(x, …)
end(x, …)a univariate or multivariate time-series, or a vector or matrix.
extra arguments for future methods.
The representation used by start and end has no
    meaning unless the frequency is supplied.
These are generic functions, which will use the
    tsp attribute of x if it exists.
    Their default methods decode the start time from the original time
    units, so that for a monthly series 1995.5 is represented
    as c(1995, 7). For a series of frequency f, time
    n+i/f is presented as c(n, i+1) (even for i = 0
    and f = 1).