--- title: "Exporting to PDF" source: https://dev.pageseeder.com/guide/documents/pageseeder_fo_config.html last_updated: 2026-08-07T17:09:54+10:00 tokens: ~9958 --- # Exporting to PDF The page describes the default mechanism for converting PSML documents to PDF and how to customize the formatting. ## Overview XSL Formatting Objects (FO) is a companion standard to XML and XSLT. Its main design objectives are to provide developers with a standards-based language that can process raw XML data into visually rich output. With XSL FO, getting richly formatted pages from native XML is a relatively straightforward pipeline compared to using a proprietary typesetting solution or the transformation from XML into a more format-oriented syntax, such as TeX. By comparison, particularly for developers with XSLT experience, FO is a familiar, standards-based syntax supported by both open source and commercial implementations. To leverage the benefits of FO, PageSeeder comes pre-configured with Apache’s FOP processor—a respected, open source FO processor. This capability enables PageSeeder to blindly export any PSML document as a PDF file. The only problem with document formats being expressed in a programming language, is that developers are often not the best people to modify the formats. For this reason, the FO implementation in PageSeeder is accompanied by a simplified language, [FOConfig](../../reference/glossary/fo_config.md), that gives non-programmers some control over the page layout and liberates developers from being responsible for all changes. The technical experience required to modify FOConfig is much closer to working with Cascading Style Sheets (CSS) or a desktop publishing app. ## Architecture To generate a PDF document, the process uses the following components: - The `pdf-export-config.xml` file that defines the formatting values of the output. - A processor to generate XSL-FO code from the `pdf-export-config.xml` file and the PSML content. - The [publish engine](../publishing.md) passes the generated code to Apache FOP which returns the documents as PDF. ## Structure The `pdf-export-config.xml` contains a list of rules in the following structure. The default rules are under the `` element with no `@label`. These can be overridden for PSML documents with specific document labels. This allows a [publication](../../reference/glossary/publications.md) consisting of multiple PSML documents to have different formatting rules for its different parts, depending on document labels (for example, `titlepage`, `frontmatter`, `appendix`). *Using multiple \ elements requires pso-pdf v0.4.0 or higher (included in PageSeeder v5.98 or higher). Previous versions require \ with no @label to be the root element.* ```xml [ [rules that override default for documents with this label] ] ... [default rules] ... ``` The rule elements allowed inside `` include the following: - `` – an element to contain the `` elements that describe the page layout. - **Region elements** – a collection of predefined layout objects such as `

`, `