Parashath Noah, Laws of Ziziyoth, Page 17:
9. (beginning) A scarf does not require ziziyoth, even though it has four corners and is wide enough to be used as a tallith. A cloak, the four corners of which are all at the front, is also exempt from ziziyoth, but a G-d-fearing person should make one of the corners rounded, in order to make sure that the garment should not require ziziyoth according to all opinions. Most people are not particular about this, but it is a laudable practice.
This learning should be in memory of Maran, HaRav HaGaon Ovadia Yosef, ztz'l.