The source XML file from which you can create a generic schema must be an export of schema from the Studio or an XML with the same XML tree structure, not any other kind of XML.
To create a generic schema from a source XML file, proceed as follows:
Right-click Generic schemas in the Repository tree view, and select Create generic schema from xml.
In the dialog box that appears, choose the source XML file from which the schema is taken and click Open.
In the schema creation wizard that appears, define the schema Name or use the default one (metadata) and give a Comment if any.
The schema structure from the source file is displayed in the Schema panel. You can customize the columns in the schema as needed.
The tool bar allows you to add, remove or move columns in your schema. You can also export the current schema as an XML file, or import a schema from an XML file, which must be an export of schema from the Studio, to replace the current schema.
Click Finish to complete the generic schema creation. The created schema is displayed under the relevant Generic schemas node.