You are correct jim, the #19 is the smaller o-ring seals that go under the rocker assembly. In the picture honda only shows you one o-ring, however there is actually four o-rings and if you click #19 on the parts catalog it will show you need four...
I've been through this a few times with this subject. It sucks cause the civic manual and the catalog show four seals in the break down, accord's do not. It's confusing if you haven't gone through it before.

Drooby, if you are to attempt changing them BE CAREFUL!.
You need to pay attention. Get the factory manual. Torqing the rocker assembly in order and to the right spec. is critical. The big bolt heads are 16 ftlbs. and the little heads are 9 ftlbs.