Package Metadata
Every taxonomy package has a metadata file, in XML format, that contains important information about the taxonomy package, such as its identifier, publisher URL, and entry points. This file is located in the ZIP archive of the taxonomy package at:
<PackageName>.zip|zip/<PackageName>/META-INF/taxonomyPackage.xml
The Package Metadata command opens, in XMLSpy, the metadata file of the active taxonomy package.
Note: You can set whether a package's metadata file is automatically opened or not when a new taxonomy package is created (Tools | Options | XBRL | Package Settings).