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October 1999

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1999.10.28 10:31 "Stupid TIFF question: tags in ascending order", by Robert Vesterman
1999.10.29 03:27 "Re: Stupid TIFF question: tags in ascending order", by Daniel Mccoy
1999.10.29 04:18 "Re: Stupid TIFF question: tags in ascending order", by Tom Lane
1999.10.29 07:15 "Re: Stupid TIFF question: tags in ascending order", by Rainer Wiesenfarth
1999.10.29 09:23 "Re: Stupid TIFF question: tags in ascending order", by Robert Vesterman

1999.10.29 03:27 "Re: Stupid TIFF question: tags in ascending order", by Daniel Mccoy

I know of no language that explicitly states that any tag should appear
only once in the file, but the fact that the spec does not specify
what a reader should do in the case of duplicate tags is a strong
indication that the authors intended it to be interpreted as strictly
ascending order.

If you want to write tiff files that other programs have a chance of reading,
you are much better off taking a conservative interpretation of points
like this.

If you are thinking of writing files like this, it's a very bad idea.

If your intention is to store extra information that way, just
get a private tag, you can make it variable length if you want
and store pretty much anything you want in it.

>Hi.  The TIFF 6.0 Specification says,
>"The entries in an IFD must be sorted in ascending order by Tag."

>Stupid question: does this mean strictly ascending order? 
>In other words, is it legal to have the same tag twice (or more)
>in a single IFD? If so, how is a TIFF reader supposed to interpret
>situations like this? Ignore the earlier tag? Ignore the later tag?
>Something else?