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 attributeThe src attribute accepts relative paths and offers error messages at import time if an error happens, such as files are missing.
The src attribute expects the file path to be relative to either the project root or the folder that contains the UXML file.
Important: You must include the file extension.
For example, to reference a UXML files that is located at Assets\Editor\UXML and a USS file that is located at Assets\Editor\USS, use any of the following formats:
src="../USS/styles.uss" or src="template.uxml"
src="/Assets/Editor/USS/styles.uss" or src="project:/Assets/Editor/UXML/template.uxml"
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.