When modify the text in HtmlEditorExtender control, HREF values appended with the Current URL + href value. Example as follows,
__This is <a href="#value1#">Link</a> for HtmlEditorExtender control__ becomes as follows
__This is <a href="http://www.mydomain.com/app1/mypage #value1#">Link</a> for HtmlEditorExtender control__
__This is <a href="#value1#">Link</a> for HtmlEditorExtender control__ becomes as follows
__This is <a href="http://www.mydomain.com/app1/mypage #value1#">Link</a> for HtmlEditorExtender control__