An InfoPath form template is typically stored as a cabinet file with an .xsn file extension, called a form template.
The form template contains several XML files, one or more script files, and, optionally , images, executable files, and XHTML files.
As you manipulate the InfoPath user interface, the in-memory version of the files that make up the form template are edited. Changes are made to the on-disk form template when the form template is saved.
The form files can be extracted from a form template using the Extract Form Files option on the File menu in design mode.
An extracted form template contains a template file that illustrates the XML structure corresponding to the form template's data source.
Each view in a form template has a corresponding XSLT stylesheet ( .xsl file) in the form template files.
The schema for a form template is stored in one or more W3C XML Schema document(s), which have an .xsd file extension.
A form template can include external COM executable files or custom scripts that can be used to provide custom functionality for the form template.
Image files can be included in a form template to provide a logo for use in the form template, for example.
Custom task panes can be included in a form template by incorporating XHTML file(s) in the form template.