Objects of this class are used to represent time periods such
  as one hour, two seconds, three years, etc.
  Partial time period are not allowed (1.5 hours will be coerced
  to an integer value using as.integer).  POSIXctp (p stands forperiod) has only one unit.
  So one hour and 2 seconds is not defined.
  To list all methods available for POSIXctp, type in the
  R console :
  methods(class='POSIXctp') # for S3 methods}
  showMethods(class='POSIXctp') # for S4 methods}
  To get back to this documentation from the R console :
  
  class?POSIXctp
{
  Objects can be created by calls of the form
  
new("POSIXctp", ...)...argument must be replaced
    by named arguments coresponding to slots of a POSIXctp (see below).
    See alsonew.POSIXctp (duration, unit)Arguments of the function correspond to object slots. SeePOSIXctpfor details.as.POSIXctp (from, ...)Converting object to
    POSIXctp.
}
{
  [object Object],[object Object]
}
{
  [object Object],[object Object],[object Object]
}
Access to POSIXctp properties{
  [object Object],[object Object],[object Object],[object Object]
}
Math and comparison functions{
  [object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]
}
{
  [object Object],[object Object],[object Object]
}
POSIXct, POSIXcti
showClass("POSIXctp")
classes