XML
RubyMine brings powerful support for XML that includes structure validation, formatting (Ctrl+Alt+L) and indentation (Ctrl+Alt+I according to the XML code style, importing unbound namespaces, viewing code structure, unwrapping and removing tags (Ctrl+Shift+Delete), generating DTD files and schemas from instance documents, as well as syntax and error highlighting, code completion (Ctrl+Space), intention actions (Alt+Enter), quick documentation look-up (Ctrl+Q), and more.
RubyMine uses Xerces 2.11, an XML parser developed by Apache Software Foundation Group.
Import XML namespaces
If you use a tag or an attribute from a namespace that is not bound, RubyMine detects the problem and shows a tooltip:
![Tooltip: Reference to an unbound namespace Tooltip: Reference to an unbound namespace](https://resources.jetbrains.com/help/img/idea/2021.3/import_unbound_namespace_tooltip_light.png)
To solve the problem, use the quick-fix that RubyMine suggests.
Press Alt+Enter. If there are multiple choices, select the desired namespace from the list.
Alternatively, hover your mouse pointer over the problem and click Create namespace declaration in the popup that opens. If there are multiple choices, select the desired namespace from the list.
Configure syntax highlighting
You can configure XML-aware syntax highlighting according to your preferences and habits.
In the Settings/Preferences dialog (Ctrl+Alt+S) , go to .
Select the color scheme, accept the highlighting settings inherited from the defaults or customize them as described in Configure colors and fonts.