There's no write up in offical Experimental Feature proposal form yet,, but there are these things about the Daffodil UDF implementation that is in forthcoming daffodil 2.5.0.

https://cwiki.apache.org/confluence/display/DAFFODIL/Proposal%3A+Feature+to+Support+User+Defined+Functions

https://github.com/apache/incubator-daffodil/tree/master/daffodil-udf

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

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