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For these reasons, I'd recommend removing HDUCLASS keywords entirely.
(Hirayama) The HDUCLASS and HDUCLASn keywords were added based on the HEASARC FITS Working Group's suggestion made when we met them at NASA/GSFC on May 28th, 2003. See also topic 002 of the latest topics of FT1 and FT2 for more details. I guess they will not appreciate it very much if we drop those keywords, although I can't (and shouldn't) speak for them, of course. In any case, I suggest to ask for their opinion before making a dicision to drop those keywords.
3. TASSIGN keyword
(Digel) TASSIGN is supposed to be where the event times were assigned, and we currently have this set equal to 'SATELLITE'. This is not strictly true, as we will need some ground processing to turn ticks of the 20 MHz clock into time since the last 1 PPS signal from the spacecraft, and we'll also need to shift GPS time to TT.
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