# XML Basics > Walk through the XML Basics sample for Visual Basic: load an XML file with Load format 10, format it with a CSS style sheet and validate it with a DTD. - **Product:** TX Text Control ActiveX - **Section:** Documentation - **Kind:** Topic - **Path:** TX Text Control ActiveX > Document Editor > Working With XML Files > XML Basics - **2046 words** - **Web URL:** https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/basics/ - **LLMs URL:** https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/basics/llms.txt - **LLMs-Full URL:** https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/basics/llms-full.txt --- Three files work together when `TXTextControl` opens an XML document: the XML file holds the data, a CSS file says how it looks and a DTD says which elements it may contain. The XML Basics sample program for Visual Basic opens such a file, and walking through its three files shows what each one contributes. The source code of the sample is in the *Samples\\vb6\\XMLBasics* sample source directory. ### Open an XML File in the Sample Program The sample program has one menu item, **Open File**. Its source code looks like the **Open File** routine of the other TX Text Control sample programs. The main difference is the *Format* parameter of the [Load](https://docs.textcontrol.com/tx-text-control-activex/reference/txtextcontrol/load-method/llms-full.txt) method, which has the value 10 to load an XML file: ```vbscript With CommonDialog1 .Filter = "XML (*.xml)|*.xml" .Flags = cdlOFNFileMustExist Or cdlOFNHideReadOnly .CancelError = True .ShowOpen If .FileName <> "" Then TXTextControl1.Load .FileName, , 10 End If End With ``` A lot happens behind the scenes, however. When you load the sample file *address.xml*, `TXTextControl` loads the XML file and also: - validates it automatically with the DTD it references; - formats it according to the CSS style sheet provided. The following sections look at the three files involved. ### The XML File The XML file contains a list of addresses: ```xml
Paul Baker Street London paul@hotmail.com George george@hotmail.com
``` Unlike an HTML or RTF file, an XML file contains no information about how the text is displayed or formatted. ### The CSS File Line 2 of the XML file references a style sheet file called *address.css*. This CSS file tells `TXTextControl` to display an address entry as a table, with the individual elements as table cells that have a border 1 pixel wide and a font size of 11 points: ```css address { display: table } address_record { display: table-row} name, street, city, email { display: table-cell; border: 1px solid; font-size: 11pt } ``` When you load *address.xml* with the sample program, `TXTextControl` displays it according to this style sheet: ![The address list loaded in the XML Basics sample and displayed as a table: one row per address record, with the name, street, city and email in bordered cells.](https://docs.textcontrol.com/assets/img/tx-text-control-activex/xml-address-table.b4498ef3.webp) A change to the CSS file can make the text appear in a completely different way. For example, the following style sheet shows a list instead of a table: ```css name { display: block; font-size: 14pt; color: blue } street, city, email { display: list-item; font-size: 11pt} ``` With this style sheet, `TXTextControl` displays the XML data as follows: ![The same address list displayed with the second style sheet: each name in large blue type, followed by the street, city and email on lines of their own.](https://docs.textcontrol.com/assets/img/tx-text-control-activex/xml-address-list-css.5fe5fef7.webp) ### The DTD File The DTD specifies which elements may occur in an XML file and how the elements are ordered or nested. The sample DTD specifies that an *address* contains one or more *address\_record* elements, which in turn contain a *name*, a *street*, a *city* and an *email*. The *street* and *city* elements are optional: ```xml ``` When it loads an XML file, `TXTextControl` checks whether the XML code is valid, which means that it follows the rules specified in the DTD. If it doesn't, an error occurs. In the following example, the required `` element has been removed: ```xml
Baker Street London paul@hotmail.com
``` Loading this XML code raises an error: ![A Tx4ole message box reporting an XML parse error: the element content is invalid according to the DTD, expecting name.](https://docs.textcontrol.com/assets/img/tx-text-control-activex/xml-dtd-parse-error.913c3d72.webp) This strict error checking is considered one of the major strengths of XML: it ensures that a document always has a certain structure, so that other applications can process it. ### Next Steps - [Loading and Saving XML Files](https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/load-save/llms-full.txt): the events for invalid and not well-formed documents and saving the CSS file. - [Editing XML Files](https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/editing/llms-full.txt): the XML editor mode and the combo boxes that insert and delete elements. - [Programming XML Documents](https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/programming/llms-full.txt): reading and changing elements with `XMLElements` in code. --- ## Nearby - **Previous:** [Programming XML Documents](https://docs.textcontrol.com/tx-text-control-activex/document-editor/xml/programming/llms-full.txt) - **Next:** [Printing](https://docs.textcontrol.com/tx-text-control-activex/document-editor/printing/llms-full.txt)