Hello all, reading this thread.
Later on it gets obvious, that it is a better solution to have an API for writing TDM header files. NI provides a free download of the TDM format description and a header writer API. This can be used to write correct TDM files without any XML schema. NI has not and will not provide a TDM schema definition. You can verifiy TDM files with any NI software which supports TDM, e.g. DIAdem, LabVIEW, LabVIEW CVI, the TDM Excel addin.
Greetings
Walter