[xep-support] Spurious validation errors for Oxygen topic.fo files

For no apparent reason I'm seeing many spurious validation errors for largeish .fo files produced from DITA source by Oxygen. The same sources were recently generating no errors. Transformation to PDF fails with error such as
 [java] ERROR: Attribute 'leader-length' cannot have a value of "".
But the topic-fo file contains no such error. To my unutotred eye it looks fine. Can anyone offer me any advice please?

Thanks
Pat Leevers

--
Eur Ing Dr Patrick Leevers
Director of Courses
Reader in Polymer Engineering
------------------------------------
Department of Mechanical Engineering
Imperial College London
South Kensington Campus
London SW7 2AZ
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Tel:   +44 (0)20 75 94 70 88
Fax:   +44 (0)20 75 94 70 17
Email: p.leevers@imperial.ac.uk
http://www.imperial.ac.uk/mepolymers
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