Create a structure that has a copy of an arbitrary subset of the fields in an existing top level structure.

In addition to specifying a subset of the fields, global and field specific options can be specified. This code is used by pvAccess clients and servers. The following are provided:

CreateRequest

Given an ascii string that selects the subset of the fields desired and the options, it generates a PVStructure that can be passed from a client to a server.

PVCopy

This is used by a server to pass data between a top level PVStructure that belongs to a client and the top level structure that has the server's data.