Download the All-In-One Update for full OCL support involving editors and the prototype Pivot implementation.
Download just the Core SDK for the limited Classic OCL used by GMF, Acceleo and QVTo.
Beware archived P2 repos retains the original non-archive mirror declaration. This causes a problem when building with Tycho. Pending a fix to Tycho Bug 560989 it may be necessary to use
as recommended in OCL Bug 560941