ReadStringRelative(
  IN  PUNICODE_STRING pRegistryPath,
  IN  PWSTR           pRelativePath,
  IN  PWSTR           pValueName,
  OUT PUNICODE_STRING pOutString
  );

Routine Description:

    This routine reads a string from a registry key parallel to the
    Netbt key - such as ..\tcpip\parameters\database

Arguments:

    pRegistryPath = ptr to the Netbt Registry path
    pRelativePath = path to value relative to same root as nbt.
    pValueName    = value to read



Return Value:

    The length of the path up to and including the last slash and a ptr
    to the first character of the last element of the string.