Non-authoritative list of some labels:

 - [ARINC 429 Labels][1]

But labels are not all standard, a specific LRU can define custom values.
Labels used by a Laseref VI IRS to output values:

[![enter image description here][2]][2]  
<sup>Source: [Honeywell][3]</sup>

 - Yaw rate = 330
 - Wind direction (true) = 316
 - Heading (true) = 314

(values are octal)

As commented by @Lnafziger, the value you are after may be derived from relative wind and heading, or is simply the heading as suggested by @DeltaLima. In any cases, there are additional parameters listed in the table. If you can describe further your needs, additional may be provided too.

You would have to confirm with the actual documentation of the specific LRU you are working with.

  [1]: https://sites.google.com/site/thel1011projectwiki/simulator-software/arinc-429-labels
  [2]: https://i.sstatic.net/UXyoB.png
  [3]: https://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/BA_brochures-documents/Laseref_VI_FINAL.pdf