Hi. First of all I want to thank the previous answers for my mails. They were very helpfull But I still have problems using serialization. In particular, I cant seem to find the correct way to register a subclass with its base class so that serliaziig through a pointer works fine. I dont know exactly where to place the BOOST_CLASS_EXPORT macros. I put them in the cpp file where all the hierarchy classes are defined, but this arises the following problem (for example): boost::serialization::void_cast_detail::void_cast_primitive<const CompositeFieldFilter, const FieldFilter>::instance is defined in both modules... (after that it mentions two modules where serialization of FieldFilter* is done) This is actually a warning for the Borland C++ compiler, but the compiled program violates the memory. Here is the output of the CodeGuard log: Error 00001. 0x400000 (Thread 0x0FC0): Exception 0xC0000005: Access violation at 0x4. Call Tree: 0x006625DC(=TMSClientProject.exe:0x01:2615DC) ../src/extended_type_info.cpp#264 0x00662697(=TMSClientProject.exe:0x01:261697) ../src/extended_type_info.cpp#280 0x00667FA8(=TMSClientProject.exe:0x01:266FA8) ../src/void_cast.cpp#41 0x00668763(=TMSClientProject.exe:0x01:267763) C:\Archivos de programa\Borland\CBuilder6\Include\stl/_tree.c#402 0x0066701D(=TMSClientProject.exe:0x01:26601D) C:\Archivos de programa\Borland\CBuilder6\Include\stl/_set.h#137 0x00666500(=TMSClientProject.exe:0x01:265500) ../src/void_cast.cpp#98 I gues somehow the relation between the base class FieldFilter and its subclass FieldFilterComposite is registered twice. But i can't find why this is done, because of my lack of knowledge of how the library works in the inside. If someone could help me with this i would really appreciate Thanks, Federico __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com