I agree. When talking about requirements I think it is important that we differ between the file format itself and applications. ODF should be able to store signatures that meet the Brazilian requirements, but as well should be able to store signatures that meet the requirements of let's say the US or China. But an application that is used let's say in Brazil has not to be capable of creating a signature that meets the Japanese requirements, nor does it has to be capable of verifying the signature of a document that has been signed in Japan.

In particular, from the few experience I have with the topic, I assume that there is not a signature that meets all local requirements that do exist in the world. We therefore need a lot of flexibility within the file format. The question is whether the flexibility that XML DSig provides is sufficient.