There are 3 files which contain the XML Schema for DFDL annotations.

DFDL_part1_simpletypes.xsd
DFDL_part2_attributes.xsd
DFDL_part3_model.xsd

These exist in the src/main/resources/xsd of BOTH daffodil-propgen and of daffodil-lib.

Maintenance of these has been undertaken in daffodil-lib, but in principle, daffodil-propgen really should be the home of these. The ones in daffodil-propgen are now out of date, which means the generated code does not see some changes.

daffodil-lib should be getting these as a managed src or something from daffodil-propgen, in the same way it gets the generated code.

In addition, there is a combined file in daffodil-lib named DFDL_model_all_parts.xsd. This is a single schema file created by merging the DFDL_part1_simpletypes.xsd, DFDL_part2_attributes.xsd, and DFDL_part3_model.xsd together. This file is needed due to DFDL-714. Unless that bug is fixed, the file DFDL_model_all_parts.xsd should be machine generated, not hand-crafted.