tinterval and timespan

I am still having problems with the timespan and tinterval types.

tinterval is defined as (abstime, abstime) but if set a value like
('2/2/1998, 2/2/1999') the result returned will be

   ["Thu Jan 01 01:04:06 1970 MET" "Thu Apr 25 07:54:08 1974 MET"]

timespan seems also worthless for me. I can define a timespan of years,
hours etc. but I am not able to use it as a time range starting from a
certain time. E. g. i would like to have a time range of 3 years starting
in 1998 and ending in year 2000. If i enter a value of '1998 years @ 2000
years' the resulting value will be '@ 3998'.

Could anyone give me a hint how to use these data types succesfully? Are
there any examples around?

Werner
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Werner Reisberger         public-key available:          voice: +49 234 540294
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