Having 2 separate OmniFocus 2 apps (2nd one for the reference)?

OmniFocus OmniFocus for Mac
#21
  1. Create new context (eg “Reference”)
  2. Switch to Contexts perspective
  3. Right-click the context “Reference” you’ve just created
  4. In Status sub-menu, choose On Hold.

Alternatively, in inspector for Contexts pespective, there’s drop-down under Context > Status: choose On Hold there.