From: "Julián Muñoz" <jmunoz@telefonica.net>

Do you know if time returned by DateTime does automatically the daylight saving time change ??? For example DateTime("CET").

It depends on which timezone you give. Some timezones have daylight saving defined, some don't. Generally the timezone support in DateTime is a confusing and poorly documented mess. There are rewrites of date and time modules in progress to make this easier in the future.