Subject: OFSP proposal Re: min and max table column keywords

From: GEORGE at HEAGIP.GSFC.NASA.GOV (Ian M George, Code 668, NASA/GSFC, USA (Usque ad mortem bibendum))
Date: Sat, 7 Aug 1993 10:56:57 -0400 (EDT)

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  | PROPOSED KEYWORDS TO GIVE THE MIN & MAX LEGAL VALUES WITHIN A COLUMN |
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At a meeting on 1993 Aug 04 of the OGIP FITS Standards Panel (OFSP) within
the Office of Guest Investigators (OGIP) at NASA/GSFC, there was a review
of keywords pairs used to give the minimum/maximum values actually contained
and the minimum/maximum legal values within a column in a FITS table.  

It was confirmed that the OGIP will use the TDMINnnn/TDMAXnnn keywords
already in common usage (eg Thompson FITSBITS post 93-aug-03) for the
minimum/maximum values actually contained within column 'nnn' of a FITS
table. 

In addition, the OFSP provisionally recommended that the TLMINnnn/TLMAXnnn
keywords be used to give the minimum/maximum LEGAL value for the numbers in 
column 'nnn' of a FITS table (as suggested by Brotzman FITSBITS 93-aug-06).

The OFSP also recommended the following to clarity:
- The datatype of the keywords should be the same as that of the table 
	column to which they refer.
- The keywords refer to ALL elements of a vector column. 
- These keywords imposed no constraints or information regarding the 
	meaning of any null data values within the data.
- It should not be forbidden to have values of (say) TDMIN < TLMIN, leaving
	it to individual applications as to what such situations implied. 
- If the keyword for the minimum value be GREATER than that for the maximum 
	value (ie TDMIN>TDMAX or TLMIN>TLMAX as appropriate), then this 
	should be taken to mean that the values had not been defined 
	and/or therefore needed [re-]calculating.

[The OFSP meeting obviously took place prior to Wayne Warren's FITSBITS 
 post on 93-aug-06]

----------------------------------- END ---------------------------------- 
Ian M George 					
NASA/GSFC OFSP
1993 Aug 07