Nominative fair use
The legal doctrine that permits using another party's trademark to refer to the trademark holder's product, when the reference is necessary, no broader than necessary, and does not suggest endorsement.
The three-prong test was articulated in New Kids on the Block v. News Am. Publ’g, 971 F.2d 302 (9th Cir. 1992): the product or service cannot be readily identified without using the mark; the use is no more than reasonably necessary; and the user does not falsely suggest sponsorship or endorsement. w3c.wiki references W3C trademarks under this doctrine; the disclaimer subsystem on every page makes the absence of affiliation explicit.