that are independent of machine-specific encoding techniques and is a precise, formal notation that removes ambiguities. Its usage can be compared to the more recent XML Schema (see also my previous post about JAXB ). The NCBI ASN1 C library is descibed here: http://www.ncbi.nlm.nih.gov/IEB/ToolBox/SDKDOCS/ASNLIB.HTML Although I still have a problem in the