XML glossary: the essential terms explained

The terms that come up when working with XML files, defined simply. Useful to understand your product feeds, sitemaps and catalog exports before editing them in a spreadsheet.

XML

XML (eXtensible Markup Language) is a text file format that structures data with nested tags, e.g. <product><price>19</price></product>. It is machine-readable and used as a standard exchange format between software (e-commerce feeds, catalog exports, sitemaps, RSS feeds).

CSV

CSV (Comma-Separated Values) is a simple tabular format where each line is a record and each column a field, separated by a comma (or semicolon). It opens in Excel, Numbers, Google Sheets or LibreOffice, making it ideal for bulk-editing data. Beware: opened by double-click, Excel rewrites long codes (EAN), leading zeros and dates its own way; import those columns as Text.

Separator (CSV)

The separator is the character that splits a CSV's columns: a comma in English-speaking countries, a semicolon in France (where the comma is the decimal mark), sometimes a tab or a vertical bar. A CSV opened with the wrong separator shows up as a single column.

Round-trip

Round-trip is the ability to convert an XML file into editable CSV, then rebuild the original XML from the edited CSV. Unlike a one-way converter, it preserves the structure (nesting, attributes, namespaces, field order) so the file can be re-imported without errors.

Tag / Element

A tag is the marker that delimits a piece of data in XML: an opening tag <title> and a closing tag </title>. The opening tag, content and closing tag together form an element. Elements can contain other elements, creating a hierarchy.

Row tag

The row tag is the repeated XML element whose every occurrence becomes a spreadsheet row: <item> in a Google Shopping feed, <product> in a catalog, <url> in a sitemap. The rest of the structure (root, containers) is recorded separately to rebuild the file. ExcelifyXML detects it automatically and shows it in the preview, where you can pick another one.

Attribute

An attribute is a key-value pair placed inside an element's opening tag, e.g. <price currency="EUR">19</price>. It carries metadata about the element. In a spreadsheet, an attribute becomes its own column (often noted with a prefix such as @currency).

Namespace

A namespace prevents tag-name collisions by prefixing elements, e.g. g:title in a Google Shopping feed or xi:include. It is declared with an xmlns attribute. A good conversion tool must preserve namespaces so the file stays valid.

CDATA

A CDATA block (<![CDATA[ ... ]]>) lets you include raw text containing reserved characters (<, >, &) without escaping them — typically HTML inside a product description. The content is treated as plain text, not markup.

XML entity

An entity is a shortcut representing a reserved or special character: &lt; for <, &amp; for &, &#233; for é. It keeps the file well-formed. Custom entity declarations (<!ENTITY>) are blocked by safe tools because they can be used for attacks (XXE).

Encoding (UTF-8, UTF-16…)

Encoding defines how characters are represented as bytes. UTF-8 is the universal standard; you also encounter UTF-16 (Salesforce Commerce Cloud exports) or ISO-8859-1. A wrong encoding produces garbled characters ("é" instead of "é"), and Excel's classic "CSV" format replaces the characters it can't write with "?": prefer "CSV UTF-8". A good tool auto-detects the encoding.

XSD / DTD (schema)

An XSD (XML Schema Definition) or DTD (Document Type Definition) describes the expected structure of an XML file: which elements, in what order, with which types. It is used to validate that a file conforms before importing it into a system.

Product feed

A product feed is an XML file (often extended RSS) listing a product catalog for a platform: Google Shopping, Meta/Facebook, price comparison engines. Each product is an <item> element with fields such as title, price, availability and id.

XML sitemap

An XML sitemap lists a site's URLs to help search engines discover them, with optional metadata (last-modified date, priority, change frequency). It follows a strict format and is submitted to Google Search Console.

Prolog / XML declaration

The prolog is the start of an XML file, before the root element. It contains the <?xml version="1.0" encoding="UTF-8"?> declaration and, optionally, a DTD. It is the only place a DOCTYPE declaration is valid — which is why attack vectors should only be scanned there.

XXE (XML External Entity)

The XXE attack abuses external entities in a malicious XML to read server files or make unauthorized requests. A safe conversion tool refuses entity declarations (ENTITY), alone or inside a DOCTYPE, and never downloads the external DTD a DOCTYPE names with SYSTEM or PUBLIC.