I can't remember how we decided to handle that. In the example jobRequest[1], option values are provided as text nodes as direct descendants of the option elements. Did we allow multiple item elements inside an option? I remember we discussed how to encode that for the XProc script in one of the face-to-face meetings but I don't know what we decided. It would definitely be useful though.

[1] https://github.com/daisy-consortium/pipeline-framework/blob/master/webservice/samples/xml-formats/jobRequest1.xml