# Schemas and DTDs > **TL;DR** > `File | Settings | Languages & Frameworks | Schemas and DTDs` for Windows and Linux > > > > `IntelliJ IDEA | Settings | Languages & Frameworks | Schemas and DTDs` for macOS > > > > `Ctrl+Alt+S` (Windows), `⌘ Comma` (macOS), `⌘ Comma` (IntelliJ IDEA Classic (macOS)), `⌘ Comma` (macOS System Shortcuts), `Ctrl+Alt+S` (XWin), `Ctrl+Alt+S` (GNOME), `Ctrl+Alt+S` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+Alt+S` (Sublime Text), `⌘ Comma` (Sublime Text (macOS)), `Ctrl+Alt+S` (NetBeans), `Ctrl+Alt+S` (Visual Studio), `⌘ Comma` (Visual Studio (macOS)), `Ctrl+Alt+S` (Eclipse), `⌘ Comma` (Eclipse (macOS))  The settings on this page define how your XML, HTML and XHTML files are validated. ## External Schemas and DTDs Local XML schema (XSD) and DTD files that are used to validate your XML files are listed in this section. Each entry is a mapping of a URI that may be referenced in your XML file onto an appropriate local schema or DTD file. Use ,  and  to create, remove and edit the mappings. See also, [Referencing XML schemas and DTDs](referencing-xml-schemas-and-dtds.html). | Item | Keyboard Shortcut | Description | | --- | --- | --- | | URI | | A URL of an XML schema (XSD) or DTD file (for example `http://www.example.org/xsds/example.xsd`) or a namespace URI (for example `http://www.example.org`, `urn:jboss:domain:1.0`). Readonly. If an XML file references the specified URI, it's validated according to a local file whose path is shown in the Location columns. | | Location | | Path to corresponding local XSD or DTD file (readonly). | | Project | | If a checkbox is not selected, a mapping is available in all of your projects. Select the mappings that you want to be available only in the current project. The selected mappings are stored in `.idea/misc.xml` or the project `.ipr` file. These files are normally shared between development team members through version control. | |  | `Alt+Insert` (Windows), `⌘ N` (macOS), `⌃ N` (IntelliJ IDEA Classic (macOS)), `⌘ N` (macOS System Shortcuts), `Alt+Insert` (XWin), `Alt+Insert` (GNOME), `Alt+Insert` (KDE), `Alt+Insert` (Emacs), `Ctrl+N` (Sublime Text), `⌘ N` (Sublime Text (macOS)), `Alt+Insert` (NetBeans), `Ctrl+N` (Visual Studio), `⌘ N` (Visual Studio (macOS)), `Alt+Insert` (Eclipse), `⌘ N` (Eclipse (macOS)) | Use this icon or shortcut to open the [Map External Resource Dialog](null) to define a new mapping between a URI and a local file. | |  | `Alt+Delete` (Windows), `⌘ ⌦` (macOS), `⌘ ⌦` (IntelliJ IDEA Classic (macOS)), `⌘ ⌦` (macOS System Shortcuts), `Alt+Delete` (XWin), `Alt+Delete` (GNOME), `Alt+Delete` (KDE), `Alt+Delete` (Emacs), `Alt+Delete` (Sublime Text), `⌘ ⌦` (Sublime Text (macOS)), `Alt+Delete` (NetBeans), `Ctrl+R, D` (Visual Studio), `⌘ R, D` (Visual Studio (macOS)), `Alt+Delete` (Eclipse), `Alt+Delete` (Eclipse (macOS)) | Use this icon or shortcut to remove the selected mappings from the list. | |  | `Enter` (Windows), `⏎` (macOS), `⏎` (IntelliJ IDEA Classic (macOS)), `⏎` (macOS System Shortcuts), `Enter` (XWin), `Enter` (GNOME), `Enter` (KDE), `Enter` (Emacs), `Enter` (Sublime Text), `⏎` (Sublime Text (macOS)), `Enter` (NetBeans), `Enter` (Visual Studio), `⏎` (Visual Studio (macOS)), `Enter` (Eclipse), `⏎` (Eclipse (macOS)) | Use this icon or shortcut to edit the selected mapping in the [Map External Resource Dialog](null). | ## Ignored Schemas and DTDs URIs for ignored schemas and DTDs are listed in this section. (If an XML file references a URI listed in this section, IntelliJ IDEA ignores that URI and doesn't mark it as an error in the editor.) Use ,  and  to add, remove and edit the URIs. See also, [Referencing XML schemas and DTDs](referencing-xml-schemas-and-dtds.html). | Item | Shortcut | Description | | --- | --- | --- | |  | `Alt+Insert` (Windows), `⌘ N` (macOS), `⌃ N` (IntelliJ IDEA Classic (macOS)), `⌘ N` (macOS System Shortcuts), `Alt+Insert` (XWin), `Alt+Insert` (GNOME), `Alt+Insert` (KDE), `Alt+Insert` (Emacs), `Ctrl+N` (Sublime Text), `⌘ N` (Sublime Text (macOS)), `Alt+Insert` (NetBeans), `Ctrl+N` (Visual Studio), `⌘ N` (Visual Studio (macOS)), `Alt+Insert` (Eclipse), `⌘ N` (Eclipse (macOS)) | Use this icon or shortcut to add a new URI to the list. | |  | `Enter` (Windows), `⏎` (macOS), `⏎` (IntelliJ IDEA Classic (macOS)), `⏎` (macOS System Shortcuts), `Enter` (XWin), `Enter` (GNOME), `Enter` (KDE), `Enter` (Emacs), `Enter` (Sublime Text), `⏎` (Sublime Text (macOS)), `Enter` (NetBeans), `Enter` (Visual Studio), `⏎` (Visual Studio (macOS)), `Enter` (Eclipse), `⏎` (Eclipse (macOS)) | Use this icon or shortcut to edit the selected URI. | |  | `Alt+Delete` (Windows), `⌘ ⌦` (macOS), `⌘ ⌦` (IntelliJ IDEA Classic (macOS)), `⌘ ⌦` (macOS System Shortcuts), `Alt+Delete` (XWin), `Alt+Delete` (GNOME), `Alt+Delete` (KDE), `Alt+Delete` (Emacs), `Alt+Delete` (Sublime Text), `⌘ ⌦` (Sublime Text (macOS)), `Alt+Delete` (NetBeans), `Ctrl+R, D` (Visual Studio), `⌘ R, D` (Visual Studio (macOS)), `Alt+Delete` (Eclipse), `Alt+Delete` (Eclipse (macOS)) | Use this icon or shortcut to remove the selected URIs from the list. The corresponding URIs become available for mapping to local XSD or DTD files. | ## See also ### Procedures [Style Sheets](style-sheets.html) ### External Links [Doc type declaration](http://en.wikipedia.org/wiki/Document_Type_Declaration)