[1] [CITE@en[Resource Hints]] ([TIME[2016-05-21 01:13:13 +09:00]]) <https://w3c.github.io/resource-hints/#h-hint-probability-pr-attribute>

[2] [CITE@en[Removed the `pr` attribute definition and examples]]
([[yoavweiss]]著, [TIME[2018-01-15 18:58:56 +09:00]])
<https://github.com/w3c/resource-hints/commit/9769790bdc00d7d7f747cc26f60a0131f851d1db>

[3] [CITE@en[Removed the `pr` attribute definition and examples by yoavweiss · Pull Request #76 · w3c/resource-hints]]
([TIME[2018-01-16 11:06:21 +09:00]])
<https://github.com/w3c/resource-hints/pull/76>