Attributes: provide extra information about the element. Norman Walsh. Structured vs. You are not supposed to sequence text-content and some elements. Tags inside the PCDATA will be treated as markup and entities will be expanded. The keyword PCDATA, inherited from ISO 8879 (which defines SGML), does indeed stand for 'parsed character data', but its denotation is narrower than you appear. ATLIST should be ATTLIST. Declaring Attributes An attribute declaration has the following syntax:. Interpreting DTD from specifications. XML - DTDs. CDATA inside PCDATA. This means that you are going to have to use something other than DTD to enforce that name contains #PCDATA or one first_name. Using these Java classes, you can populate your data structure (your listOfPoints ). The lxml lib is well suited for this: With sample. dtd. Within mixed content models, text can appear by itself or it can be interspersed between elements. DTD: Stands for "Document Type Definition. Give an example of valid XML for the provided DTD document R b. 妥当性検証を. Place #PCDATA in DTD mixed Content. xml against laptop. The DTD input to the XML C++ class generator is an XML document containing a DTD, or it is an external DTD. For CDATA. XML. Name - unique name of the document to describe the DTD. I want to define a dtd for my xml document. <!--===== Special DTD Notation: * = 0 or more occurrences (optional element and repeatable) ? = 0 or 1 occurrences (optional element at most 1) + = 1 or more occurrences (required element and repeatable) | = choice, one or the other but not both Note: * MMO stands for MetaMap Machine Output. Learn more about TeamsSo, just to clarify - does "custom DTD" mean "DTD which is independent/different from any DTD which may be specified in the content of the XML file"? – Peter Sep 11, 2011 at 1:561. <!ELEMENT Description (#PCDATA|Courseref)* > However, I want to enforce a more strict constraint. b) dtd file. Thus we declared the external DTD file in the xml file. Used to define the body element to be of type “#PCDATA” Using DTD for Entity Declaration: To define special characters or strings used in a document, a DOCTYPE declaration can be used. <!-- html. DTD (Document Type Definition, česky Definice typu dokumentu) je jazyk pro popis struktury XML případně SGML dokumentu. DTDs define the structure of a class of documents through element and attribute-list declarations. The attribute gender="male" should be added to name in the instance (XML data itself). The DTD language constructs are element and attribute-list declarations. The following is an example of a DTD used for defining an automobile:XML DTD Validation In making up the slides for this lecture, I borrowed material from several sources: “Data on the Web” Abiteboul, Buneman and Suciu “XML in a Nutshell” Harold and Means “The XML Companion” Bradley The validation examples were originally tested with an older parser and so the specific outputs may differ from those. An element can contain a number of. subelements. mzjn. the leaf level element types are described by the data type (#PCDATA) - parsed character data; Each attribute of an element type is also described in the DTD by enumerating some of its properties (OPTIONAL, etc. 23 Operating Systems: AIX, Linux, WindowsAlternatively, the DTD specification can be placed in a separate file, say phone. I want to have an element titled "Description", which may have any inter-leaved sequence of a BookRef and PCDATA. テキストデータを内容に含む場合は、以下のように要素型宣言中に”#pcdata”と記述します。 <!element 要素名 #pcdata > 内容にテキストデータのほかに子供要素も含める混在内容のときは、以下のように要素の指定の前に、”#pcdata”と記述します。DTD 简介 文档类型定义（DTD）可定义合法的XML文档构建模块。它使用一系列合法的元素来定义文档的结构。 DTD 可被成行地声明于 XML 文档中，也可作为一个外部引用。 内部的 DOCTYPE 声明 假如 DTD 被包含在您的 XML 源文件中，它应当通过下面的语法包装在一个 DOCTYPE 声明中： <!DOCTYPE root-element [element. 1 Answer. #PCDATA is not appropriate for the type of an attribute. The following describes how a DTD defines a document type. Any elements defined in a DTD can be used in these documents, along with the predefined tags and attributes that are part of each markup language. 2. We used such a DTD in Chapters 9 and 10 when we created XHTML documents. Learn more about Teams1. i have spend a few hours with this but no one of my friends knows xml. These are two different concepts. type parameter entity with the value "#PCDATA" that gets used in a quantity element's content model gets converted to an RNG named pattern with the same name. getClassLoader (). In this chapter we will discuss about DTD Attributes. Here is the example code taken from a book: dtd = Nokogiri::XML::Document. !DOCTYPE note defines that the root element of this document is note. Internal DTD are embedded in the XML document itself. dtd in the file movies. 427; asked Nov 12, 2015 at 4:34. Russ Cox's article "Go 1. Well-formed − If the XML document adheres to all the general XML rules such as tags must be properly nested. Add a comment. The root is chapters and under root I have two main elements chapter1 and chapter2 and under each I have sub-elements. The DTD used by a XML document is declared after the. • the products element contains a sequence of product sub elements, one for each product in the database. 7. )In my DTD document I get the error: The markup in the document preceding the root element must be well-formed. DTD is one of ways to define the structure of XML documents, i. tdjfdjdj tdjfdjdj. Tags inside the CDATA text are not treated as markup and entities will not be expanded. > characters are allowed in attribute values. To specify a mixed-content model, just list #PCDATA along with the. 427; asked Nov 12, 2015 at 4:34. DTD stands for Document Type Definition. Later same colleague asked me for a favor. The lowest level of definition in a DTD is that something is either CDATA or PCDATA: Character Data, or Parsed Character Data. Java Code: This method takes 2 parameters one xml message and another one dtd details. Dans le modèle de contenu d'un élément d'un élément, #PCDATA indique que l'élément contient (peut contenir) "tout texte ancien". DTD stands for Document Type Definition. edit: if you want to maintain the parsed character data in the td element along with the new tags, you can define a mixed content element. Improve this question. e. <mail> • Document instance (representative of the document class) • XML declaration informs the XML prosessing system about the version and the character set. . Because the DTD defines values for more than one document, this EntitlementRef portion is actually not part of the Entitlement definition. method == "POST" Edit. Under DTD, there is no difference between numeric type data and text type data. The name of these sub-elements are identical in both chapter1 and chapter2. DTD is a document-type definition. the asterisk is required. DTD:Table A-15 Statistics Request DTD Elements. . With the parens it’s expecting an element named "EMPTY". 5. Sử dụng DTD để kiểm tra tài liệu XML. XML allows fewer content types (CDATA, ID, IDREF, NAME, ?) XML is very particular about mixed content. XML • XML stands for EXtensible Markup Language. e. There are multiple XML declarations. 通过 dtd 验证的xml是“合法”的 xml。 形式良好的 XML 文档 “形式良好”的 XML 文档拥有正确的语法。 在前面的章节描述的语法规则： XML 文档必须有一个根元素 XML元素都必须有一个关闭标签 XML 标签对大小写敏感 XML 元素必须被正确的嵌套 XML 属性值必须加引号. 01 Answer. xml; dtd; cdata; pcdata; Siva R. You have no attribute declared in your DTD. 900; asked Nov 14, 2016 at 17:36Unfortunately, a tag name can't begin with a number. 1 vote. 1 Answer. Parsed Character Data ( PCDATA) is a data definition that originated in Standard Generalized Markup Language (SGML), and is used also in Extensible Markup Language (XML) Document Type Definition (DTD) to designate mixed content XML elements. Well, the only occurence of 'version' in your document is in the pseudo at the top, where the quotes appear curly. Validation is the process of checking a document. DTD's form part of the W3C's XML Standard, but are typically considered to be a separate schema technology and are not typically used in conjunction with other. When any XML file refers DTD file, it validates against those rules. The keyword PCDATA, inherited from ISO 8879 (which defines SGML), does indeed stand for 'parsed character data', but its denotation is narrower than you appear to be thinking. In an element's content model, #PCDATA says that the element contains (may contain) "any old text. 0. Element declarations name the elements allowed within a document of this type, and specify whether and how. dtd. DTD Overview. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java,. <!ELEMENT employee: It defines that the employee element contains 3. are the elements and each element must have its own definition within the DTD. Open-source XML validators include xmllint (built on libxml),. DTD 教程 DTD（文档类型定义）的作用是定义 XML 文档的合法构建模块。. I'm using following statement in my XML DTD. Problems preventing your XML document from being well-formed, including: There internal DTD subset syntax is not constructed properly. Norm is a Senior Application Analyst at ArborText, Inc. En DTD, le contenu texte d'un élément est noté #PCDATA et est entièrement libre. DTDs actually predate XML; they are a reduced hand-me-down from SGML with the core syntax almost completely intact. You probably have to do this by hand. XML must be well-formed. Valid XML Documents A "Valid". Its main purpose is to define the structure of an XML document. DTD stands for document definition. dtd laptop. parseDoc. So I don't know any automated way of creating the model from a XML. (A text declaration is basically the same as the <?xml?> declaration. I'm trying to validate following . In other words you can say that a parsed character data means the XML parser. Most converters follow these steps, but Trang converts the parameter entities to RNG named patterns and references those from content models. I need to be able to allow the user to view the available attributes and their values as defined by the dtd so they can set the attributes on the content. xml; dtd; cdata; pcdata; Siva R. They can be used in an XML document to escape characters (such as &) that would otherwise be interpreted as markup. the asterisk is required. – Boldewyn May 10, 2010 at 14:01 Hmmm, is. For example, the following describes the Element Type Declaration that designates the content of "product_name" as a text string:Alternatively, the DTD specification can be placed in a separate file, say phone. But you haven't escaped the second. 0" encoding="UTF-8"?> <!DOCTYPE statements SYSTEM "sql. The opposite is true for XML Schema, which are verbose, but. I think the attributes medID on medicine and docID on doctor are fine. 0. g. 1 Answer. You probably need to remove the parentheses from around " (EMPTY)". A DTD is identified with the DOCTYPE declaration, which follows the XML declaration and precedes document elements. For instance, we can validate laptop. The DTD must also capture all the primary key and foreign key constraints". An attribute declaration has the following syntax: <!ATTLIST element-name attribute-name attribute-type attribute-value>. <!-- html. The WDDX DTD allows for multiple encodings of binary data. This will allow name to contain character data or be empty. The CDATA keyword in an attribute declaration has a different meaning than the CDATA section in an XML document. 1 Answer. #PCDATA must come first in the mixed content declaration. 0" encoding="UTF-8"?> <!DOCTYPE PERSON [ <!ELEMENT lista_plac_dokument (autor, informacje_o_dokumencie. e. So basically the DTD CDATA type is a string type with no restrictions placed on it, it can contain any textual data (as long as its suitably escaped ). <!ELEMENT family (Name+)> <!ELEMENT Name (FirstName+, LastName, Phone*)> <!ELEMENT FirstName (#PCDATA)> <!ELEMENT LastName (#PCDATA)>. When this policy should be applied. When. A DTD is text-based. Why did XHTML have PCDATA inside script and style tags?Home / My courses / UGRD-IT6316-2213T / FINAL EXAMINATION / FINAL EXAMINATION. • XML was designed to be both human- and. Here is a SAX parser example you can rely upon. XML DTD and Schemas. Specify the valid tag sequence/arrangements. Declaração Final - e, por fim, a declaração do DTD é fechada através de um suporte e. Tarzan. As shown in Listing 3. In the internal subset of DTD, references to parameter entities are not allowed. I am validating a XML file with external DTD using XMLStarlet from Cygwin. In order to validate your XML and DTD you just need to setValidating: DocumentBuilderFactory dbf = DocumentBuilderFactory. child1, child2. You ask when you might want to do this. Each of the pcdata indexes (PCDATA $1, PCDATA $2, and so. Apr 23, 2013 at 12:25. DTD tak například vymezuje jazyky HTML a XHTML. You shouldn't need all. CDATA is text that will NOT be parsed by a parser. If you want to combine the DTD and XML instance, add a DOCTYPE declaration and put the DTD declarations in the internal subset (add a prolog ). Tags inside the PCDATA will be treated as markup and entities will be expanded. An XML attribute is always in the form of a name-value pair. テキストデータを内容に含む場合は、以下のように要素型宣言中に”#pcdata”と記述します。 <!element 要素名 #pcdata > 内容にテキストデータのほかに子供要素も含める混在内容のときは、以下のように要素の指定の前に、”#pcdata”と記述します。 DTD 简介 文档类型定义（DTD）可定义合法的XML文档构建模块。. Khai báo Element – Tag và Attributes. , tags) and specifies the element requirements by following the ELEMENT name with either: 1 Answer. Here is the example code taken from a book: dtd = Nokogiri::XML::Document. This is supported by the production in that section. To get your XML to validate as-is,. An element can have any number of unique attributes. While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. 489. Svaki korisnik tog XML. DTD determines how many times a node should appear, and how their. setValidating (true); // since the default value is false. The PUBLIC keyword indicates that the DTD is widely used (e. You have to use an external DTD, i. Yes this is pretty much HTML links within the Etymology and Footnote elements, I have tried doing <!ELEMENT a (#PCDATA)> and <!ATTLIST a href CDATA #IMPLIED> and it hasn't worked. " (With exceptions as noted below. A DTD is identified with the DOCTYPE declaration, which follows the XML declaration and precedes document elements. DTD. <!ELEMENT value (#PCDATA)> Entitlement values are untyped strings. For example, a DTD's quantity. TYPES OF DTD • Internal DTD: DTD can be embedded into XML document • External DTD: DTD can be in a separate file . asked Jul 25, 2011 at 15:22. Consider the following snippet - DTD <!DOCTYPE hotels_list [ <!ELEMENT hotels_list ( hotel+ ) > <!ELEMENT hotel ( id, name, stars, Facilities, Address, distance_from. The DTD specification file can be used to validate documents. Note that this is an alternative to using XML entities to represent graphics in XMetaL; with the CTM it is not necessary to use entities and the ENTITY attribute type. An element tells the parser to parse the document from the specified root element. you can achieve the same flexibility. 2, tel is a leaf element that contains only text while email is an empty element: <!ELEMENT tel (#PCDATA)> <!ELEMENT email EMPTY>Your DTD is still incomplete so it won't validate (you need to declare the age attribute for a start). The XML document must have an associated DTD. 2, tel is a leaf element that contains only text while email is an empty element: <!ELEMENT tel (#PCDATA)> <!ELEMENT email EMPTY> Your DTD is still incomplete so it won't validate (you need to declare the age attribute for a start). It's not possible in XML. Hot Network Questions Why is it politically controversial that the President of India referred to herself as the "President of Bharat"? Speed of light postulate in special relativity in inertial vs. DTD stands for Document Type Definition. It defines the legal building blocks of an XML document. The three things a DTD specifies. you should reference them in the <!ELEMENT td> definition. . Double click on the dataflow. PCDATA in this context means mixed content, elements may contain character data, optionally interspersed with child elements. Parts of an XML Document • A XML document itself consist of: • XML declaration (can be missing) • Document Type Definition (DTD can be missing) • Root element (eg. It can be used to validate the length of the binary object after decoding. <!ELEMENT phoneNumbers (title, entries)> <!ELEMENT title (#PCDATA)> <!ELEMENT entries (entry*)> <!ELEMENT entry (name, phone, city?)>XML DTD MCQs and Answers With Explanation: XML DTD (Document Type Definition) is an important aspect of XML (Extensible Markup Language), a widely used markup language for organizing and sharing data across different systems and applications. Is there a way to ensure that when the xml is validated, that every tag has some text in it through the DTD? Or does that need to be done at the application. 1, but using attributes instead of. You cannot use any element names other than those in this set. Sorted by: 1. Teams. External DTDs. An XML DTD can be either specified inside the document, or it can be kept in a separate document and then. Hello fisrt time posting. In simple terms this means a " Name " has to start with a letter or ':' or '_'. In my XML document I get: An element type is required in the declaration of element type "viewer_rating". dtd 教程 dtd（文档类型定义）的作用是定义 xml 文档的合法构建模块。 dtd 可被成行地声明于 xml 文档中，也可作为一个外部引用。 现在开始学习dtd! dtd 新闻实例 <!doctype newspaper [ <!element newspaper (article+)> <!element article (headline,byline,lead,. The ArbortextDTD Editor is a text-based. parse(%{<!ELEMENT rubycookbook (recipe+)> <!E. And in your XML change <cr:course xmlns = ". x database--> <!ELEMENT wInsightDb (Columns?,the leaf level element types are described by the data type (#PCDATA) - parsed character data; Each attribute of an element type is also described in the DTD by enumerating some of its properties (OPTIONAL, etc. As per your created DTD you have only one child element student under root element students. Generally, name data originates in a. Why Use a DTD?. [1] The string "Anton Smith" would be considered as parsed character data . Once you need to define a content model allowing text ( #PCDATA) and elements - also named mixed content - , you MUST define it that way : (#PCDATA | element1 | element2 |. 9, we're keeping the content the same, but this file doesn't include the <!DOCTYPE>. Follow. Somebody please explain. dtd document. Software Engineering Observation B. In a DTD, the type of an attribute that contains text must be CDATA. Và ở phần này mình sẽ giới tiếp về Document Type Definition (DTD) cho mọi. , which are not declared in your DTD. , the document’s metadata. No DTD can make that distinction, because DTDs have no mechanism for constraining #PCDATA content. Last is "id" who should be #CDATA, becouse in the future I declarate it more in XSD document. Any help would be appreciated. If you develop applications, wait until the specification is stable before you add a DTD. dtd document, as well as an internal declaration. DTD has validated elements and attributes that are defined inside the DTD document. DTD identifier is an identifier for the document type definition, which may be the path to a file on the system or URL to a file on the internet. Example. In the dvdlibrary. dtd”. @DanielHaley It is a single big file, but I'm supposed to integrate it to show the connections. d) Both a and b. py) and that really depends on how you understand your data. Since they will all simply contain text, we can use a very simple element declaration: <!ELEMENT airline (#PCDATA)>. Semi-structured data • Observation: most data have some structure, e. Try. Connect and share knowledge within a single location that is structured and easy to search. With. Connect and share knowledge within a single location that is structured and easy to search. The XML representation of data using attributes is shown in Figure. v. XML parser examines the data and ensures that it doesn't contain entity. Create flashcards for FREE and quiz yourself with an interactive flipper. The following sender-element could be part of an XML-document:New search experience powered by AI. 4,310 8 50 72. ContactInformation isn't allowed as a child of Company (and ContactInformation and it's children (PhoneNumber, Fax, and EMail) aren't declared at all in the DTD) The element ServicesList isn't declared in the DTD. In general, you can use these entity references anywhere. In order to generate the XSD file properly, use the following procedure: Create all the required Java Beans. 4. @DanielHaley It is a single big file, but I'm supposed to integrate it to show the connections. Although DTDs are often criticized because of this need to learn a new syntax, the syntax itself is quite terse. " A DTD defines the tags and attributes used in an XML or HTML document. Consider the following snippet - DTD <!DOCTYPE hotels_list [ <!ELEMENT hotels_list ( hotel+ ) > <!ELEMENT hotel ( id, name, stars, Facilities, Address, distance_from. CDATA sections are not declared in the DTD; they are simply used when needed. XML DTD Validator. DTD - XML Building Blocks Previous Next The main building blocks of both XML and HTML documents are elements. Java Code: This method takes 2 parameters one xml message and another one dtd details. DTD 实例. There are four kinds of declarations in XML: element type declarations. You can also use normal text within the XML document, such as in element contents and attribute values. For a value to be a valid IDREF the following must be true:-. Although XML documents can be accompanied by a document type definition (DTD) that defines the structure of the documents, the presence of a DTD is not mandatory. If you come across any feel free to edit the answer or leave a comment. and your XML instance will become:. DTD defines what tags or blocks of an XML. . 0" encoding="UTF-8"?> <!DOCTYPE PERSON [ <!ELEMENT lista_plac_dokument (autor, informacje_o_dokumencie. dtd Document Type Definition for the HyperText Markup Language (HTML DTD) $Id: html. What is the right formatting of DTD when an Element can both contain PCDATA and an other ELEMENT. DTD とは. I'm trying to validate following . Problem preventing your XML document from being valid: The A2 plant has to have at least one climate child element. Clarifying the intended semantics. Và ở phần này mình sẽ giới tiếp về Document Type Definition (DTD) cho mọi. DTD Sintaxe - Um XML DTD pode ser especificado dentro do documento, ou ele pode ser mantido em um documento separado e, em seguida, o documento pode ser associado ao DTD documento para usá-lo. e. The . method == "POST", the API policy is executed only if the request method is a POST. Is there a way to ensure that when the xml is validated, that every tag has some text in it through the DTD? Or does that need to be done at the application level? Thanks for your help. A DTD can be declared inside an XML document as inline or as an external recommendation. , a developer of industrial stength SGML authoring and publishing tools, though we need to say that the words here are his. 4. The critical difference between DTDs and XML Schema is that XML Schema utilize an XML-based syntax, whereas DTDs have a unique syntax held over from SGML DTDs. non-inertial frames Do all artificial satellites have engines?. Example instance (the DTD can be external, but I used an internal subset because it was easier to test):DTD is the acronym for Document Type Definition. Phần tiếp theo mình sẽ giới thiệu về XML DOM nhé, 1 trong những phần quan trọng của XML. For example, the document shown above could contain the following <!DOCTYPE> tag:. dtd, as referenced in ch06-wonders. xml, contact. When an element will contain only character data, declare the element in this manner: <!ELEMENT elementName (#PCDATA)> PCDATA . 23. It is a set of markup affirmations that actually define a type of document for the SGML family, like GML, SGML, HTML, XML. In general, you can configure XMetaL to recognize a DTD's image element (s) by using the CTM file that is part of the XMetaL customization associated with the DTD. > characters are allowed in attribute values. DTD has validated elements and attributes that are defined inside the DTD document. , the value. Example. 现在开始学习DTD! DTD 新闻实例 <!DOCTYPE NEWSPAPER [ <!ELEMENT NEWSPAPER (ARTICLE+)> <!ELEMENT ARTICLE (HEADLINE,BYLINE,LEAD,. XML DTD • PCDATA is text that will be parsed by a parser. To validate against DTD in a separate file, we can use the –dtdvalid option followed by the file path to the DTD. DTD Declaration • A DTD can be declared inline inside an XML document, or as an external reference. g. The DTD specification file can be used to validate documents. One clumsy possibility is the W3C Markup Validator. NOTE: When you first submit the XML, be sure that you don't have "Validate against external XML schema" selected! DTD and Schema are two different things. Share. Drag a query into the dataflow & connect it to DTD format. The DTD is NOT complete and would have incomplete elements for sure. DTD (Document Type Definition) je stariji način određivanja pravila strukture XML dokumenta. An object-relational mapping is performed in two steps. CDATA vs PCDATA CDATA . A Document Type Definition (DTD) is a document that describes the structure of an XML document, what elements and attributes it contains and what values they may have. You need to add spaces between your element names and the content model (the left parenthesis). Teams. Your first case introduces the possibility of not marking up a name into separate first and last names. The Client Call Addin Request DTD describes the format of the XML document that is used when calling an addin. This Use Case illustrates this requirement by means of a flexible document type named Book. technically qualifies as allowing mixed content, but does not allow any elements to be mixed in. PCDATA in this context means mixed content, elements may contain character data,. The problem is that I need to be able to have those values read from the dtd to present the user with the. DTD-Miner: a tool for mining DTD from XML documents. A variable declared in a function is also called a (n) ____ variable. Ở phần 1 mình đã giới thiệu sơ lược về XML là gì. Given below are my note. The two mappings can optionally be combined for a direct DTD-to-database mapping, as is done in most software today. The XSD schema described by the following schema. PCDATA is text that will be parsed by a parser. DTD の正確な記述方法は少し面倒なものですが、ここでは、HTML の文法を定義する際に用いられている DTD に限定して、その定義内容を紹介し. It is officially recommended by the World Wide Web. Similarly, CDATA is Character Data. When a DTD is absent the validating parser can’t verify the data format but can attempt to interpret the data. You just need to reference the parameter entities. If you wanted to allow more than one "helper", you could use IDREFS: The element could look like this (or it could be the same as above; as long as there is more. 183 views. 4. This use case is based on an input document named "book. Yes and you are very close with your example. !ELEMENT note defines that the note element must contain four elements: "to,from,heading,body". 1 Answer. XMLのDTDのエラーがわからない. The valid XML documents under this DTD must have a tree structure with as much nesting as possible. Think of character data as the text found between the start tag and the end tag of an XML element. I'm using following statement in my XML DTD. <!ELEMENT phoneNumbers (title, entries)> <!ELEMENT title (#PCDATA)> <!ELEMENT entries (entry*)> <!ELEMENT entry (name, phone, city?)>Each element needs to have its own attribute declaration (ATTLIST). dtd,v 1. PCDATA. Yes, absolutely. Here is an example of XML validation that uses Java: XML Validation. xml (do a view-source, line 3) Where to put the DTD file. That's one of the major limitations of DTD: a given element name always has the same content model. Attribute gives more information about an element or more precisely it defines a property of an element. Document Type Definition (DTD) is a schema language for XML inherited from SGML, used initially, before XML Schema was developed. Q&A for work.