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**PRE(**// //[ //prefix //] **)**

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| **PRE** | Provides a label prefix for complex data structures. |
| //prefix// | Acceptable characters are alphabet letters, numerals 0 through 9, and the underscore character. A //prefix// must start with an alpha character or underscore. By convention, a //prefix// is 1-3 characters, although it can be longer. |

The **PRE** attribute provides a label prefix for a FILE, QUEUE, GROUP, REPORT, or ITEMIZE structure. PRE is also valid on a LIKE declaration to provide a separate prefix when LIKE is used to declare another copy of a complex data structure.

PRE is used to distinguish between identical variable names that occur in different structures. When a data element from a complex data structure is referenced in executable statements, assignments, and parameter lists, the //prefix// is attached to its label by a colon (Pre:Label).

PRE is essentially a legacy attribute which is being replaced by a more flexible method to distinguish between identical variable names that occur in different structures: Field Qualification syntax. When referenced in executable statements, assignments, and parameter lists, the label of the structure containing the field is attached to the field label by a period (GroupName.Label).

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The use of PRE with TYPE in a FILE structure is not supported.

**Example:**

**MasterFile FILE,DRIVER('Clarion'),****PRE****(Mst)     !Declare master file layout**

**Record      RECORD**

**AcctNumber   LONG   !Referenced as Mst:AcctNumber or MasterFile.AcctNumber**

**            END**

**           END**

**Detail      FILE,DRIVER('Clarion'),****PRE****(Dtl)     !Declare detail file layout**

**Record       RECORD**

**AcctNumber    LONG  !Referenced as Dtl:AcctNumber or Detail.AcctNumber**

**             END**

**            END**

**SaveQueue  QUEUE,****PRE****(Sav)**

**AcctNumber  LONG    !Referenced as Sav:AcctNumber or SaveQueue.AcctNumber**

**           END**

**G1     GROUP,****PRE****(Mem)                !Declare some memory variables**

**Message STRING(30)                   !with the Mem prefix**

**       END**

**G2     LIKE(G1),****PRE****(Me2)             !Another GROUP LIKE the first containing same **

** CODE                                !variables using the "Me2" prefix**

** IF Dtl:AcctNumber <;> Mst:AcctNumber !Is it a new account**

**  Mem:Message = 'New Account'        !display message**

**  Me2:Message = 'Variable in LIKE group'**

** END**

** IF Detail.AcctNumber <;> Masterfile.AcctNumber    !Same expression**

**  G1.Message = 'New Account'         ! display message**

**  G2.Message = 'Same Variable in LIKE group'**

** END**

**See Also:**

[[reserved words.htm|Reserved Words]]

[[field qualification.htm|Field Qualification]]