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Starting with In-Portal 5.0.0 there is ability to create "theme.xml" file under "_install" folder in theme. This file holds meta-information that is used to interact with theme templates. You can even create "_install" folder under each module sub folder in one theme, e.g.
/themes/theme_folder/_install/theme.xml- in-portal file/themes/theme_folder/*in-commerce*/_install/theme.xml- in-commerce module file
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