What does this code mean in Modx? Is it a template?

Question

MODX

The tpl.mFilter2.filter.checkbox chunk from the mSearch2 plugin at the very beginning contains the following code:
{var $key = $table ~ $delimeter ~ $filter}
What is it? Where can you read more about this? I wonder if it is possible to display content in this way depending on the value of the variable.
Here is the code for the chunk itself:

{var $key = $table ~ $delimeter ~ $filter}
<label for="mse2_{$key}_{$idx}" class="{$disabled}">
    <input type="checkbox" name="{$filter_key}" id="mse2_{$key}_{$idx}" value="{$value}" {$checked} {$disabled}/>
    <span>{$title}</span>&nbsp;<sup>{$num}</sup>
</label><br/>

Answer 1

this is a Fenom template engine documentation
content depending on the variable can be displayed.

Answer 2

Adds a resource count to the header. It looks like these are filters from mSearch2.