An extension section of a discovery pattern is a section that allows you to modify or extend the functionality of an existing pattern without customizing it. An extension section can contain shared libraries, which are reusable code snippets that can be invoked from any pattern or extension section. Shared libraries can be used to define common functions, variables, or constants that are used across multiple patterns or extension sections. Shared libraries can also be used to override the default behavior of some built-in functions, such as identification or classification12. References = 1: ITOM: Extending Discovery/Service Mapping Patterns - GlideFast ServiceNow 2: How to Create Discovery Pattern Extensions and Why to Use Them

The Set Parameter Value operation is used to assign a value to a variable in a Discovery pattern1. The syntax for this operation is as follows2:
Set Parameter Value: <Variable Name> = <Value>
The <Value> can be either a constant or an expression. To declare a constant, unchanging value, one must use quotes around the value. For example2:
Set Parameter Value: $name = "John"
This assigns the string "John" to the variable $name. The quotes indicate that the value is a constant and will not change. The other options, hash tag, brackets, and dollar sign, are not used to declare a constant value.
They have different meanings in the syntax of the Set Parameter Value operation. A hash tag (#) is used to indicate a comment2. Brackets ([]) are used to access an element of an array or a map2. A dollar sign

The functionality shown in the image is related to the Tracked Configuration files feature of ServiceNow Discovery. This feature allows Discovery to track changes in configuration files on Windows and Unix hosts and store them as configuration items (CIs) in the CMDB1. To modify this functionality, such as adding or removing files to track, changing the file attributes to capture, or defining the CI relationships, one needs to edit the Discovery Pattern that is associated with the Tracked Configuration files classifier2. A Discovery Patternis a series of operations that tell Discovery how to find and identify an application or a configuration file on a host3.
:
1: Tracked Configuration files - Product Documentation: San Diego - ServiceNow
2: Tracked Configuration files pattern - Product Documentation: San Diego - ServiceNow
3: Patterns and horizontal discovery - Product Documentation: Tokyo - ServiceNow