# XML tools - overview

This product provides a comprehensive visual XML development environment. The tool set includes components for building DTDs, XML schemas, and XML files.

The following XML tools are available:

The XML editor is a tool for creating and viewing XML files. You can use it to create new XML files, either from scratch, existing DTDs, or existing XML schemas. You can also use it to edit XML files, associate them with DTDs or schemas, and validate them.

The DTD editor is a tool for creating and viewing DTDs.

The XML schema editor is a tool for creating, viewing, and validating XML schemas. You can use the XML schema editor to perform tasks such as creating XML schema components and importing and viewing XML schemas.

Exercise caution when opening large files with any of the XML editors. If the memory limits of the workbench are exceeded, it will abruptly close without saving any data (and without warning or error messages). The number of elements in an XML file, not its size, is the best indicator of how much memory will be required. Memory requirements also depend on what else is open in the workbench - in some cases you can open a 15 megabytes file, but in other cases a one-megabyte file may cause problems. Therefore, we recommend you save all data in the workbench before opening large XML files. This is a permanent restriction.

The behavior of the XML parser when encountering an unresolvable URI (for example, in a DOCTYPE declaration) is to report a fatal IO error and stop any further processing. An unresolved URI is seen neither as a syntactic nor a semantic error and as such, the parser does not attempt to handle it. Essentially, the document remains unchecked. This is a known problem.