Validating an XSL file
The XSL validator ensures that the XSL file is well-formed. It tries to detect any static errors, that is, an error that can be detected in a style sheet before execution starts.
To validate an XSL file:
In the Navigator view, right-click your XSL file and click Validate XSL File..
A dialog opens, indicating if the XSL file was successfully validated or not. If the file is invalid, any errors will appear in the Problems view. For more details about a problem, right-click on the problem message and click Show Details
You can set up a project's properties so that different types of project resources are automatically validated when you save them. From a project's pop-up menu select Properties > Validation. Any validators you can run against your project are listed in the Validation page.