Subject: BINTABLE TTYPE values in all caps?

From: edgar at oldstyle.astro.wisc.edu (Dick Edgar)
Date: 10 May 1995 15:29:06 GMT

In the process of developing a set of FITS files for release, we observe
that in all known cases the column names in FITS BINTABLE extensions
seem to be in all capital letters.  These are the values of the TTYPEnnn
keywords in the BINTABLE header.  Is this practice required,
recommended, or just left over from Fortran and VMS usage?

I can find nothing in the NOST FITS standard, or in the BINTABLE
specification paper (Cotton, Tody, & Pence, A&A this spring) that
requires this.

Also, since these data are x-rays destined for archival at the HEASARC,
I would appreciate some comment from the HEASARC OGIP on this issue.

many thanks
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Richard J. Edgar  (edgar at uwast.astro.wisc.edu)
University of Wisconsin--Madison, Department of Astronomy
"An astrophysicist is someone who sees something working in practice,
and wonders whether it will work in principle." -- Harvey Liszt

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From: Arnold Rots <arots at xebec.gsfc.nasa.gov>
Date: Thu, 11 May 1995 11:35:40 -0400 (EDT)

Indeed, there is nothing in the standard that says you can't
use lower (or mixed) case.  It's a habit that's left over
from ..., well, you said it already.

I am using mixed case in the XTE FITS files for most character
string values, to improve readability.  The OGIP/HEASARC
position is that one can use whatever one wants, in this
respect, but should not regard those string values case-
sensitive.  I.e., use:

TTYPE1  = 'ThisColumn'

but consider it equivalent to:

TTYPE1  = 'THISCOLUMN'

  - Arnold Rots

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From: edgar at oldstyle.astro.wisc.edu
Date: Thu, 11 May 95 10:40:31 -0500

> but consider it equivalent to:

This is pretty much what we wanted to do for DXS FITS files.  However,
perhaps I should point out that the Ftools seem to care about case in
column names; if you have TTYPE1 = 'ThisColumn' in the FITS file, and
you try to use FPLOT to plot THISCOLUMN, it can't find it.  The IDL
astro library is worse: it upcases your inputs but *not* the names from
the FITS file, so it simply can't find columns that aren't upper case.
Easy enough to fix, but the end user shouldn't have to do that.

Thanks for the reply.

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