This is the sequence number for fields, and it affects the order in which the fields are displayed. Just always start at 1.
The description of a dimension. This must be clear to everyone, because this description is used throughout the rental process.
Indicates whether the field is mandatory to enter when a dimension object is created at a customer. For example, if you make the 'Name' field mandatory, the Name field will always have to be filled in when entering a person at a customer. The field cannot then be skipped.