The second page of the four page customize event dialog is pretty self evident. Each internal data field is presented along with three controls: export, required and access level.

Export

Use this checkbox to specify that the field should be included in the export output. If checked the field will be included, if unchecked the field will not be included. Note that certain fields (such as the display data fields) are exported based on settings on the export form itself so are not listed here.

Required

Check fields that you wish to make required in this column. When the event edit form is submitted these fields will be checked. If any required field is not specified by the end user he/she will be forced to enter a non-empty value for the field before the event will be accepted. On this page of the dialog, if a checkbox is disabled then the field is either always required (such as subject and start date) or it doesn't make sense to make it required (such as dates or the deleted indicator which is an export only field).

Access level

The access level dropdowns specify which permission level an end user must have to be able to see a field. All fields are visible to all users by default. You might use this for example to present contact information only to logged in users. You may specify a different access level for each field.