Thank you very much, this sounds encouraging !
Unfortunately my ActiveState installation bites me again.
There is no DateTime::Span module there available, only DateTime::Span::Common. If I start with DateTime::Span::Common (just a use declaration to test) it dies "Can't locate DateTime/Span.pm in @INC ..."
Trying to install with cpan from the command line brings an error message
"Warning: Cannot install DataTime::span, don't know what it is.
Try the command
to find objects with matching identifiers.
There is not DateTime::Duration module, only Datetime::Duration::Fuzzy.
Sorry! There is
DataTime::Duration there, sorry, I have used the false script.