You can specify the namespace and assembly to use types from the top of the HBM files:
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="MyCorp.MyAssembly" namespace="MyCorp.MyAssembly.MyNamespace">
Can you use types from multiple assemblies / namespaces inside the same mapping file, and if so, what is the syntax for this?
As Ben said, you can use qualified type names.
However, a common practice in NHibernate is to put the mapping for each class in a separate file, which simplifies its support.
, (, XYHeader XYDetail).
, ( ), .
HBM, , , :
Namespace.TypeName,Assembly.Name
, .