Difference between key , duplicate order key , Alternate Search key

Record Field Properties:

Difference between key , duplicate order key , Alternate Search key

Key:

•     Helps us in uniquely identifying a row of data.
•     The primary key must be the first field in the record, followed by the next most important key, and   so on.
•     Key fields are followed by duplicate order keys, in order of importance, then by fields that are not keys.
•     Can be used as Search key or listbox item or both.

Duplicate order key

• Allows duplicate values.
              Example. Same Employee having multiple degrees at same date.
• Do not create a related language record with a duplicate order key.
• Can be used as listbox item.

Alternate Search key 

•  This displays the field in the Advance Search and builds indexes on this field. 
•  This will help in fast retrieval of data.
•  Also keep in mind that, as these database indexes consume disk space, mark the field alernate search  key only if it is really required.
•  Alternate key fields can be placed anywhere among regular fields (non-key fields), in any order. They do not need to be grouped.
•  It is displayed in the Advanced search and can be used as Listbox item.

All these 3 keys are mutually exclusive.