[R] timeSeq and TimeDate analog in R ?

[markleeds at verizon.net]

Hi All : I am attempting tomove a large amount of code from Splus to R and I was hoping that there was an equivalent in R of the Splus functions timeSeq and timeDate ?

I did an RSiteSearch but nothing came up ? 
If the equivalent functions are part of some package, that's fine.
Thanks a lot.

                                       Mark