Multi-block messages from host to node

A multi-block message from host to node consists of entire subdomain virt arrays for all the local blocks on the target node. Therefore, routine issnddhs does nothing more then send all the subdomain virt arrays on the host to the nodes and isrcddnd does nothing more then receive these entire arrays and copy them to the virt arrays on the node. Each sub message has the form:

iblock

number of the target block

itrans

type of the transported quantity

ilev

time level at which this transport of information occurs.