# u01ad user exit

User exit u01ad retrieves a value from an attribute of an item in a
 file. The next line of the Proc specifies the file information.

## Syntax

```
u01ad
file.name item-ID attribute.ref code.number
```

## Parameter(s)

| file.name | Name of the file. If the file name is prefixed with an asterisk, the dictionary portion of the file is accessed. | |
| --- | --- | --- |
| item-ID | Item name. | |
| attribute.ref | Attribute name (or number). | |
| code.number | a | Outputs to the alternative output buffer. |
| p | Outputs to the primary input buffer. | |
| s | Outputs to the current output buffer. | |
| t | Outputs to the terminal. | |
| v | Verifies that the file exists. | |
| va | Verifies that the attribute exists. | |

## Description

This function allows *indirect* references to values from the input and output buffers by
 using these special symbols:

| % | Indicates the current input buffer value. |
| --- | --- |
| # | Indicates the current output buffer value. |

 Note:
 The same function can be performed with the correlative:

```
a0(tfile.reference;xn;; a/amc)
```

 where *file.reference* is the name of the file, *n* is the
 n value to retrieve, and *a/amc* is the attribute-mark count to use.

## Example(s)

| Direct Reference | |
| --- | --- |
| pq u01ad control-file co.name 1 s xcan’t find co.name or control.file | Reads attribute 1 of the item called co.name in the file named control-file and places it in the current output buffer. |
| Indirect Reference | |
| pq u01ad %2 %3 %4 p xsomething went wrong... d0 | Reads the attribute number as defined in the fourth location of the input buffer, using the item-ID from the third location and the file name from the second location. |

## See also

- [a (algebraic) processing code](https://d3codex.com/processingcodes/a-algebraic-processing-code/)
- [PROC processor user exits](https://d3codex.com/proc/proc-processor-user-exits/)
- [u11ad user exit](https://d3codex.com/proc/u11ad-user-exit/)
- [u21ad user exit](https://d3codex.com/proc/u21ad-user-exit/)

---
Source: https://d3codex.com/proc/u01ad-user-exit/ - part of the D3Codex reference.