Xml libraries in python (and probably some other languages) do not automatically differentiate between null, empty string (and not specified field on dynamic object?).
I had to process some .trsx files with empty dbid attribute on speaker, generated from python.

To prevent further problems, from now on: empty string value of dbid is handled same null value.
trsx XSD was modified to forbid empty string in dbid attribute
Buffering (preloading of trsx into memory buffer) was added to the transcription loading. It have no perceivable impact on performance and it can behave better in some cases, because XmlTextReader is reading the stream without internal buffering.
Also, buffering enables xml schema validation (some stream cannot be read twice and i will not recreate trsx_v1 deserialization from scratch to work with XDocument)

Sample validation (for debuging only) was added to WPF transcription