---
title: "Structuring macros, metadata, and other value-pairs"
url: "https://axoflow.com/docs/axosyslog-core/4.28/chapter-concepts/concepts-value-pairs/"
last_modified: "2023-09-02T18:02:36+02:00"
---

> For the complete documentation index, see [llms.txt](https://axoflow.com/docs/axosyslog-core/4.28/llms.txt).

# Structuring macros, metadata, and other value-pairs

*Available in AxoSyslog 3.3 and later.*

The AxoSyslog application allows you to select and construct name-value pairs from any information already available about the log message, or extracted from the message itself. You can directly use this structured information, for example, in the following places:

- [`amqp()`](https://axoflow.com/docs/axosyslog-core/4.28/chapter-destinations/configuring-destinations-amqp/index.md) destination
- [`format-welf()`](https://axoflow.com/docs/axosyslog-core/4.28/chapter-manipulating-messages/customizing-message-format/reference-template-functions/index.md) template function
- [`mongodb()`](https://axoflow.com/docs/axosyslog-core/4.28/chapter-destinations/configuring-destinations-mongodb/index.md) destination
- [`stomp()`](https://axoflow.com/docs/axosyslog-core/4.28/chapter-destinations/configuring-destinations-stomp/index.md) destination
- or in other destinations using the [format-json()](https://axoflow.com/docs/axosyslog-core/4.28/chapter-manipulating-messages/customizing-message-format/reference-template-functions/index.md) template function.

When using `value-pairs`, there are three ways to specify which information (that is, macros or other name-value pairs) to include in the selection.

- Select groups of macros using the `scope()` parameter, and optionally remove certain macros from the group using the `exclude()` parameter.
- List specific macros to include using the `key()` parameter.
- Define new name-value pairs to include using the `pair()` parameter.

These parameters are detailed in [value-pairs()](https://axoflow.com/docs/axosyslog-core/4.28/chapter-concepts/concepts-value-pairs/option-value-pairs/index.md).

---

[Specifying data types in value-pairs](https://axoflow.com/docs/axosyslog-core/4.28/chapter-concepts/concepts-value-pairs/specifying-data-types/index.md)

[value-pairs()](https://axoflow.com/docs/axosyslog-core/4.28/chapter-concepts/concepts-value-pairs/option-value-pairs/index.md)

Last modified September 2, 2023: [Fixes xrefs and formatting errors (ecec42e0)](https://github.com/axoflow/axosyslog-core-docs/commit/ecec42e093b96e9315fa07d0aa2eeac0b24193b5)