Bug?

Try using <div align="center"> instead of <center>

it doesn’t change, sorry ??
It always inserts a new / in the old code

That ‘/’ is a closing tag, it’s a good thing. It should be there.

I’ve never used that slash before, in that position, and so seems to think the author of this link:
https://www.davesite.com/webstation/html/chap04.shtml

That slash is absolutely correct and valid XHTML.
The link refers to HTML ( and that page is badly wrong too)

WP is not causing an error there.

Dave’s site is talking about HTML. WP uses XHTML which is more than a little different. Without the ‘/’ your XHTML won’t validate.

Edit: Damn Podz beat me to it.

thanks a lot and sorry ??