Today I discovered that the Calendar Event has five userDefined fields available for use. Because the template help has no information about these, I will quickly supply the information for you here.

To access these variables, you need to mdoify the Default Calendar Event template and Default Calendar Event Edit templates.

To display the value, modify the Default Calendar Event and add:

        <tr>
            <td class="heading">
                <div style="padding:4px;">User Defined 1</div>
            </td>
            <td class="day">                            
                <div class="eventWrapper">
                    <tmpl_var userDefined1>
                </div>
            </td>
        </tr>

To display the value, modify the Default Calendar Event Edit and add:

        <tr>
            <td class="label" style="text-align:right;vertical-align:top">UserDefined 1</td>
            <td><tmpl_var formUserDefined1></td>
        </tr>

The variable names are as such:

userDefined1, userDefined2, userDefined3, userDefined4, userDefined5

and

formUserDefined1, formUserDefined2, formUserDefined3, formUserDefined4, formUserDefined5