< and the width of the frame is used instead.
> and the width of the [[Frame]] is used instead.
word-wrapping.el by RafaelSepúlveda? is a MinorMode much like AutoFillMode. The difference is that it fills the paragraph when point reaches the fill-column, instead of waiting for a white space character.
Additionally, if auto-fill-mode is not active, fill-column is ignored and the width of the Frame is used instead.
See also LineWrap.