[xsl] XSL:FO - How to wrap non-word strings in table cells?

I have long non-word string values in a table that are running off the page. 
Most of these values contain no spaces at all.
I would like them to wrap to the next line in the same cell, without inserting a hyphen or other character. 
Hyphenate="true" doesn't seem to apply here since the values are not real words.
It is not possible to predict the values.
Any advice on how to do this wrapping is greatly appreciated.
Jon


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