> For the complete documentation index, see [llms.txt](https://brlabelectronics.gitbook.io/tutorials-1/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://brlabelectronics.gitbook.io/tutorials-1/the-app-code/writing-the-code/comment-header.md).

# Comment Header

It is always good practice to have a comment header that describes what the application code does. This is also a good place to list out the Blynk data streams that you created for later reference. 

For Example you can create a comment block as shown below.

{% code lineNumbers="true" %}

```arduino
/*----------------------------------------------------------------
Title: Blynk Relay Tutorial 
Written By: (Place Your Name Here)
Date Written: (Place Date here)
Description: This code was written to control 4 individual relays
on an Particle Argon Relay Shield using four switch widgets on a 
Blynk web interface and moblile app.

Blynk Data Streams:
Relay 1 (V0)
Relay 2 (V1)
Relay 3 (V2)
Relay 4 (V3)
----------------------------------------------------------------------*/
```

{% endcode %}