Pre Default & Post Default

Post Default Value:

The value used for an empty field when the record is initially written to the database. This value is not used if the field is left empty on subsequent updates to the record. The post-default value for the field is used even when the field is not exposed in the user interface.
This property is not validated for a calculated field.

Pre Default Value:

The value used for an empty field when a new record is created through an Add New Record or Copy Record operation. The value can be changed by the user before the record is written to the database. The pre-default value for the field is used even when the field is not exposed in the user interface.
This is true for Copy Record operation only if the No Copy property is set to TRUE.
This property is not validated for a calculated field.

Long List:

A TRUE or FALSE value that specifies whether the Siebel application should attempt to position the cursor on the current value in a long list of values.
When you specify Long List = TRUE for a picklist list, the Siebel application does not keep focus on the current record.
A value of TRUE means that the picklist returns a large set of values, so to scroll through that list of values and position the cursor on the current value in the field could be very costly from a performance standpoint. For this reason, Long List does not keep focus.
TRUE = Recommendation is to set this attribute to TRUE if pick list is expected to contain more than 500 records.