As mentioned previously, ePublisher Designer breaks up the transform process into a series of pipelines, or groups of similar stages. Each stage defines an .xsl file to be executed which creates a portion of the output target. ePublisher Designer uses a combination of the Format's Pipelines, the GlobalFiles record (files.info), XSLT parameters and the root match template in a given XSL file to perform the action to be executed in a stage. These stages are defined in the format.wwfmt file located in each Format directory. The format.wwfmt file defines all of the pipelines and steps necessary to create a given output, and the relationships that each of these have to one another. There is no preconceived order in which pipelines fire; the ePublisher Designer engine calculates at run time the order in which each pipeline will fire, based on pipeline dependencies.

ePublisher Designer processes files based on type rather than by name. Each stage defines an .xsl file to be executed which creates a portion of the output target. All ePublisher Designer XSL stylesheets define four parameters by default. These are as follows:

In addition, XSL stylesheets are passed all parameters defined for the current stage in format.wwfmt. Parameters passed to each XSLT file are usually used to load the various XML node sets needed for the current stage. For example, a stage may need to take information recorded in the Behaviors pipeline and merge it with information in the Links pipeline. The location of information generated in each stage is stored in the files.info file. Future stages may consult files.info to learn the location of previously generated information needed to complete that particular stage. Similarly, when that stage is complete, it will send notice to the files.info file that the information it has created is available for future stages to use if necessary.