Oh, I apologize. I just realized the doc was a little bit cryptic. Using type 6 as an example, this is the entry in the doc that describes what type it is:
"\x06" e_name
Undefined —
Deprecatedso the hex value is the value of the type and the most right hand side is the description of the type.
I rechecked the code again and I realized that this gets printed out when you have documents that have an undefined value. But the export should still proceed with the undefined value being translated into a blank string "". Was your export failing?