The ICustomDictionarySource type exposes the following members.
A custom appendix string that can be used to distinguish different custom dictionaries. It is passed the CustomAppendix of the KaxSpell object. This way one can create different dictionaries for John and Mary.
The directory that contains the custom dictionary file. Necessary only for file based storage -- it is set to the physical directory corresponding to KaxSpell's DictPath property setting.
The language for the custom dictionary. It is usually a culture name like en-US or de-DE.