Why does using CHARFORMAT2 to set superscript or subscript apply the change to the entire RichTextBox?

Question

WHAT I HAVE:
Visual Basic 2019, WinForms, NET 4.0+

MY PROBLEM:
I've written code to use SendMessage and the CHARFORMAT2 structure to set superscript or subscript to a selected region of text. The problem is, it doesn't just apply a style to the selection only; it applies it the the entire text box! What am I doing wrong?

Please give an answer ASAP, in VB.NET, and as simply as possible.

Answer 1

I figure it out, I have the set one of the parameters to SCF_SELECTION!