  The $K\times 2$ and $2\times K$, Multiple-Input Multiple-Output (MIMO) X
channel with constant channel coefficients available at all transmitters and
receivers is considered. A new alignment scheme, named \emph{layered
interference alignment}, is proposed in which both vector and real interference
alignment are exploited, in conjunction with joint processing at receiver
sides. Data streams with fractional multiplexing gains are sent in the desired
directions to align the interfering signals at receivers. To decode the
intended messages at receivers, a joint processing/simultaneous decoding
technique, which exploits the availability of several receive antennas, is
proposed. This analysis is subsequently backed up by metrical results for
systems of linear forms. In particular, for such linear forms,
Khintchine--Groshev type theorems are proved over real and complex numbers. It
is observed that $K\times 2$ and $2\times K$, X channels with $M$ antennas at
all transmitters/receivers enjoy duality in Degrees of Freedom (DoF). It is
shown that incorporating the layered interference alignment is essential to
characterize the total DoF of $\frac{2KM}{K+1}$ in the $K\times 2$ and $2\times
K$, $M$ antenna X channels.
