[Rd] objects with tsp attribute but no class

[William Dunlap]

What is the intended difference between objects of class "ts",
which must have an attribute called "tsp", and objects with that
attribute but not that class?

Calling time series oriented functions like time() or window()
on vectors of numbers produce the classless objects with the
tsp attribute.  Should methods for atomic vectors check for
the tsp attribute and do special things for it?

I was wondering if it was just to be compatible with S or S+,
where in ancient (pre-class) times, the ".Tsp" attribute indicated
that you were dealing with a time series, just as the presence
of of a ".Dim" attribute meant the object was a matrix.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com