Every e-mail message or form is grouped into a message class. All forms of a given message class have identical behavior because they have the same set of pages, controls, and script code. Certain base message classes provided with Microsoft® Outlook® define behavior for common functionality, and can be extended to provide additional functionality. This means you don't need to start from scratch to create a custom form.
In the case of LitCrit, F & M developers started with the message class IPM.Post, the base class for forms meant to be posted. In other words, a form of this base message class was used as a template for creating the LitCrit form; when you save a form, it takes the extension .oft, which stands for Outlook Template.
It is best to choose the template (an Outlook form of a given message class) that most closely supports the task — in this case, writing and reading critiques. There are many types of forms to choose from (such as task, appointment, meeting, and e-mail forms) but F & M developers chose the IPM.Post form, which is used to post items and responses in a public folder. This form is typically used for online discussions and document tracking.
Most post functionality was already present in the basic Post form; the developers built on it by adding and deleting fields and adding custom script.
Note To identify the base message class of a form you have open in design mode (see Opening a Form in Design Mode), click Publish Form As on the Form Design toolbar. The message class on which this form was based is displayed at the bottom of the Publish Form As dialog box. When you type a more specific name for your form, this name is appended onto the base form name, turning for example IPM.Post into IPM.Post.EnhancedLitCrit.