  We introduce the multiplexing of a crossing, replacing a classical crossing
of a virtual link diagram with multiple crossings which is a mixture of
classical and virtual. For integers $m_{i}$ $(i=1,\ldots,n)$ and an ordered
$n$-component virtual link diagram $D$, a new virtual link diagram
$D(m_{1},\ldots,m_{n})$ is obtained from $D$ by the multiplexing of all
crossings. For welded isotopic virtual link diagrams $D$ and $D'$,
$D(m_{1},\ldots,m_{n})$ and $D'(m_{1},\ldots,m_{n})$ are welded isotopic. From
the point of view of classical link theory, it seems very interesting that
$D(m_{1},\ldots,m_{n})$ could not be welded isotopic to a classical link
diagram even if $D$ is a classical one, and new classical link invariants are
expected from known welded link invariants via the multiplexing of crossings.
