I know that green edging strips are used on bag tags for flights originating in the EU. Some (but not all) of the tags on bags I've checked in Malaysia have had orange edging - what does that signify? I've also seen tags with red edges - what does that signify? And are any other colors used?
The colored strips are just for the convenience of the baggage handling staff. They make it easier to find your own company’s tag or luggage. Some countries also mandate particular colors so that they know which luggage originates from which country.
As long as the colored area remains outside of the barcode’s quiet zone, they can be any color or multiple colors or even text and logos.