Spatio temporal data modeling and variography - function (gstat) variogramST

Hi, I am working with spatio temporal data using spatio temporal kriging.
I saw that the function variogramST also considers days (and months, and
years) to determine temporal lags for the creation of spatio temporal
variogram. I would like to ask if someone could tell me if this is correct
and, if yes, if it would be possible to let the funcrion variogramST
(gstat) to consider only hours, minutes and seconds of the times associated
to each data for the definition of temporal lags.

Kind regards.