After loading the files contents initially and then after each modification through the users actions, the contents are checked by the embedded XML parser.

This first checks for the XML content being well formed, which among other things means, that each opening tag is matched by a closing tag, attribute values are quoted properly etc.

If an XML schema is attached to the FileHandler, the thus parsed contents will then be validated against this schema for conformance.

If any error occurs during those checks, an according status message is displayed in the status area at the top and the main text area will display the full error text as its tooltip. In addition the location at where the error occurred is underlined. This might sometimes be hard to spot, depending on the nature of the error. However, the error message usually indicates the line and column number of the location where the error was detected.

The parser used for this checking will only be considering the loaded XML data and XInclude support is turned off. This can lead to errors because of missing IDs to which any present IDREFs are referring.

If the content is considered valid, this will be indicated by an according status message at the top. That status message will always also indicate the nature of the data being checked (e.g. “XML”, “XML Schema”, “DocBook 4.5” or something the like).

Configuration of the syntax highlighting used by this FileHandler can be accomplished by customizing the text styles of the application.