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In the right part at the bottom ( PDF Editor Kepler - Merging Documents for JIRA Panel) you can change the files order using the Up and Down arrows and choose the files to be exported using Select / Unselect action
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Once you have selected and ordered your files, you can start the export using the Export Action, please see below:
Note that The "Export" Action will be export combine all selected attachements on one in the order you specified into one single PDF file which will then be attached to the Jira issue.
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