Write an OnProtectChange event handler to allow modification of text with the protected attribute. The StartPos and EndPos parameters indicate the beginning and end of the range of text that would be affected by the modification, where 0 is the first character in the text. To allow modification of protected text, set AllowChange to true. 

To set or unset the protected attribute for a section of text, select the text and use the Protected property of the rich edit control's SelAttributes property. To cause text to have the protected attribute by default, use the Protected property of the rich edit object's DefAttributes property. 

DefAttributes 

SelAttributes 

SelLength 

SelStart