NTTypes: timeStamp and TAI

[Ralph L. <Ral...@gm...>]

Colleagues,

Currently, the NT time stamp type is defined as

structure timeStamp
     long secondsPastEpoch
     int  nanoseconds
     int  userTag


ITER will use TAI [1] as well as UTC time standards.
There might be cases of mixed use of both within a single machine, even 
within a single EPICS DB.

Any client must know which standard is being used, as conversion is 
non-trivial because it needs tables that have to be updated usually 
every year. (Which is one reason why for embedded systems and/or PLCs it 
should be avoided having to do these transformations.)

How well do NTTypes handle this? Would it be useful to add an optional enum?

Cheers,
~Ralph

[1] http://en.wikipedia.org/wiki/International_Atomic_Time