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| //label// | **KEY(**[**-/+**]//field//,...,[**-/+**][//field//]**)** [,**DUP**] [,**NAME( )**] [,**NOCASE**] [,**OPT**] [,**PRIMARY**] |

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| //label// | The label of the KEY (PROP:Label). |
| **KEY** | Declares a dynamically maintained index into the data file. |
| **-/+** | The - (//minus sign//) preceding a key component //field// specifies descending order for that component. If omitted, or + (//plus sign//), the component is sorted in ascending order. |
| //field// | The label of a field in the RECORD structure of the FILE in which the KEY is declared. The //field// is a key component. A field declared with the DIM attribute (an array) may not be used as a key component. |
| **NAME** | Specifies the disk file specification of the KEY (PROP:NAME). |
| **DUP** | Allows multiple records with duplicate values in their key component fields (PROP:DUP). |
| **NOCASE** | Specifies case insensitive sort order (PROP:NOCASE). |
| **OPT** | Excludes, from the KEY, those records with null (zero or blank) values in all key component fields (PROP:OPT). |
| **PRIMARY** | Specifies the KEY is the file's relational primary key (a unique key containing all records in the file) (PROP:PRIMARY). |

A **KEY** is an index into the data file which is automatically updated whenever records are added, changed, or deleted. It is used to access records in a different logical order than the "physical order" of the file. A KEY may be used for either sequential file processing or direct random access.

A KEY may have more than one component //field//. The order of the components determines the sort sequence of the key. The first component is the most general, and the last component is the most specific. Generally, a data file may have up to 255 keys (and indexes) and each key may be up to 255 bytes, but the exact numbers are file driver dependent.

**Example:**

**Names   FILE,DRIVER('Clarion'),PRE(Nam)**

**NameKey  KEY(Nam:Name),NOCASE,DUP    !Declare the name key**

**NbrKey   KEY(Nam:Number),OPT         !Declare the number key**

**Rec      RECORD**

**Name      STRING(20)**

**Number    SHORT**

**         END**

**        END**

** CODE**

** Nam:Name = 'Soft Velocity'          !Initialize key field**

** GET(Names,Nam:NameKey)              !Get the record**

** SET(Nam:NbrKey)                     !Set sequential by number**

**See Also:**

[[set  initiate sequential file processing .htm|SET]]

[[get  read a record or entry .htm|GET]]

[[index  declare static file access index .htm|INDEX]]

[[build  build keys and indexes .htm|BUILD]]

[[pack  remove deleted records .htm|PACK]]