forms - What file defines the relation between front-end and methods in the code-behind file?

Question

When I have a form element in the view:
create.cshtml

<form method="get">
    ...whatever
</form>

and we have a model in the code-behind file:
create.cshtml.cs

public class CreateModel : PageModel 
{
    //...whatever
    public void OnGet()
    {

    }
}

the form will call OnGet(). I understand that this is a standard and is followed in most frameworks, but that means it must be defined somewhere in .NET. What file defines this standard and if we can, can we change it (for understanding's sake)?

question from:https://stackoverflow.com/questions/65626065/what-file-defines-the-relation-between-front-end-and-methods-in-the-code-behind

Answer 1

Waitting for answers