just some part of a mental image picture where the preclear is looking at blackness. It is part of some lock, secondary or engram. In Scn it can occur (rarely) when the pc is exterior, looking at something black. It responds to R3R.(Routine 3R, Standard Dianetics technique) (HCOB 23 Apr 69) In the 50s, and probably later, anyone who could not see facsimiles or mock ups was regarded as a black case. Since Scientology tended to concern itself with visual perceptions, this was a serious thing, and attempts were made to "handle black cases". (Antony Phillips)