The second block in the recommended structure is the parameter block.
Parameters are the data, passed to the script in the job call, needed for the script to function.
Parameters must be declared. By declaring them right at the start of a script a person reading the script immediately has an idea what is needed to make the script work.
A second advantage of declaring parameters at the beginning of a script is in troubleshooting: by comparing the list of passed parameters to the list of needed parameters an error is easily found.
Use descriptive names for the parameters: avoid names like file1 or file2; instead use descriptive names.
Use comment when you suspect something might not be clear to a third party.
The use of capitals in parameter names is not prescribed in the ITP/Script language. The only recommendation is to be consistent. If started with using initial capitals remain doing so at least throughout the script but preferably in all scripts.