You will encounter three types of fields in most screens:

• Mandatory fields
• Optional fields
• Conditional fields

• Mandatory Fields
  Of the many fields in a screen, the inputs to some may be mandatory. This means that you cannot save the record without giving a valid input in such fields.
• Optional Fields
  
• Conditional Fields
  
• Option lists
  Inputs to certain fields can be picked up from the option list provided with the field. The option list will contain values that are valid inputs to the field.