A BOM can be emitted at the beginning of the text artifacts produced by Hime. This may be a problem for artifacts consumed by tools such as graphviz dot. The BOM is emitted in cases as explained in: System.IO.StreamWriter.
For example when a constructor like this is used:
new StreamWriter(file, false, Encoding.UTF8)
This should be replaced by the use of
UTF8Encoding instance without the BOM.