A historical sample of user-defined variables. This sample
is associated with the usrHistoryControlEntry that set up the
parameters for a regular collection of these samples.
The usrHistoryControlIndex value in the index identifies the
usrHistoryControlEntry on whose behalf this entry was created.
The usrHistoryObjectIndex value in the index identifies the
usrHistoryObjectEntry on whose behalf this entry was created.
For example, an instance of usrHistoryAbsValue, which represents
the 14th sample of a variable collected as specified by
usrHistoryControlEntry.1 and usrHistoryObjectEntry.1.5,
would be named usrHistoryAbsValue.1.14.5