<tsd:content> closed </tsd:content>

Default is “closed”, meaning instances containing instances not defined in the schema are rejected. The value “open” means instances are stored even if they contain structures not defined in the schema. You should coordinate this value with structureIndex.

I tried to use open with a schema, but in tsd sequence attribute, if i don’t follow the correct order in the sequence i get an error due to the correctness of the sequence.
Is it right?
Any example when i have to use open or closed?

Open content allows that additional elements and attributes not described in the schema are allowed in the XML instance. However, all restrictions (order, cardinality, datatype, etc)given in the schema do still apply to the respective elements/attributes.