I am using TortoiseSVN 1.6.6, and the docx merge is working fine. Check your SVN settings β Diff Viewer β Advanced ...
There is a table of tyrannical programs like mime. For docx, I see "wscript.exe" C: \ Program Files \ TortoiseSVN \ Diff-Scripts \ diff-docx.js "% base% mine // E: javascript".
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