> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Syntax

> Code syntax reference for the NLP Extraction Rules activity — comments, existence conditions, token templates, and right-hand-part operations.

* [Existence condition](/vantage/documentation/advanced-designer/activities/nlp-extraction-rules/code-syntax/existence-condition)
* [Token template](/vantage/documentation/advanced-designer/activities/nlp-extraction-rules/code-syntax/token-template)
* [Additional check](/vantage/documentation/advanced-designer/activities/nlp-extraction-rules/code-syntax/additional-check)
* [Right-hand part](/vantage/documentation/advanced-designer/activities/nlp-extraction-rules/code-syntax/right-hand-part)

| Operation | Syntax                  | Description                                                                                                                                                                | Example                                                                                                                        |
| :-------- | :---------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :----------------------------------------------------------------------------------------------------------------------------- |
| comment   | `//` or `/* comment */` | Usual comments syntax. Double slash specifies that no code to the right of it will be executed on that line. Slash + asterisk lets you comment out multiple lines at once. | `[ a: @NERAddress ]` `// checks the existence of an address named entity on a token and assigns it to a new variable called a` |