Thanks for the reply.
I searched on that file name and found.
Is this common to all characters and related to the overall spec of the projectile?

The ProjectileMoveScript.cs is what makes the projectile work.
If you inspect any UFE projectile at runtime you will see this script on it.
Any custom code you want to be doing with projectiles should be done in this script.

It's also possible to access public variables of ProjectileMoveScript.cs via your own scripts, so you don't necessarily need the source version of UFE to make a custom projectile.

Is the following understanding correct?

・「ProjectileMoveScript.cs」 is a file common to each character.
・When 「Projectile」 in each character's Move Editor is edited and executed, the script is read and used as a reference.
・The code in the common file contains the details of each character's individual props.
「More complex designs can be created by writing individual prop details directly in 「ProjectileMoveScript.cs」.

Is "ProjectileMoveScript.cs" the parent class and the newly created custom script a child class?
Is it mean that in the custom script created,
write the code regarding the complex projectile of the move I want to create?

Thanks.
These "where to write the program code?" etc,
Is the knowledge that is a prerequisite for starting work unique to this UFE2 asset?
Or is it something that can be determined by knowing Unity as a whole (C#)?

I am checking the UFE2 script (I bought the source code version) while learning C# from scratch, but I am not sure.
I could not find any information on how to set up the environment for source code modification in C# to handle the source code as a project on visualStudio. Is there any site or other information that would be helpful?