  We investigate the constraint equations of the Lounesto spinor fields
classification and show that it can be used to completely characterize all the
singular classes, which are potential accommodations for further mass dimension
one fermions, beyond the well known Elko spinor fields. This result can be
useful for two purposes: besides a great abridgement in the classification of a
given spinor field, we provide a general form of each class of spinor fields,
which can be used furthermore to search for a general classification of spinors
dynamics.
