In a UXML file, you can use the <Template> and the <Style> elements to reference other UXML or USS files. The two elements both accept either an src attribute or a path attribute.
src attributeUse the following syntax for the src attribute:
src="<path-to-file>/<file-name-with-extension>"
Any errors during import, such as missing files, trigger an error message.
You can use a relative or an absolute path:
Assets folder and begin with a / or project://database/. For example, /Assets/myFolder/myFile.uss or project://database/Assets/myFolder/myFile.uss./. For example, ../myFolder/myFile.uss.
Note: To reference a file from packages, use the absolute path of the package file that starts from the Packages folder. For example, /Packages/com.unity.package.name/file-name.uss or project://database/Packages/com.unity.package.name/file-name.uss. you must use the format of com.unity.package.name rather than package name for the package name.
path attributeThe path attribute uses the Unity Resources mechanisms, but doesn’t offer error reporting at import time and doesn’t allow relative paths.
The path attribute accepts files located in either the Resources folder or the Editor Default Resources folder, with the following rules:
Resources folder, don’t include the file extension. For example, write path="template" for a file located at Assets/Resources/template.uxml.Editor Default Resources folder, you must include the file extension. For example, write path="template.uxml" for a file located at Assets/Editor Default Resources/template.uxml.