  We review how Elko arise as an extension of complex valued four-component
Majorana spinors. This is followed by a discussion that constrains certain
elements of phase freedom. A proof is reviewed that unambiguously establishes
that Elko, and for that matter the indicated Majorana spinors, cannot satisfy
Dirac equation. They, however do, as they must, satisfy spinorial Klein-Gordon
equation. We then introduce a quantum field with Elko as its expansion
coefficients and show that it is causal, satisfies Fermi statistics, and then
refer to the existing literature to remind that its mass dimensionally is one.
We conclude by providing an up-to-date bibliography on the subject.
