Data

Builds on XML Schema to provide a small number of intrinsic data types plus the means to declare new types. These are used to declare the form's data model. XForms is targetted at a less skilled audience than XML Schemas, and we need to be sensitive to this.

Logic

Leverages familarity with spreadsheets and existing electronic forms packages: required fields, dependent fields, running totals, etc.

Presentation

A combination of style properties and presentation elements that bind to the form's data.