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Re: Replacement character list limitation?

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  • Subject: Re: Replacement character list limitation?
  • Date: Mon, 23 May 2005 10:28:15 -0600
Stonie,

>Date: Mon, 23 May 2005 16:07:35 +0000
>From: "Stonie R. Cooper" <address@hidden>
>Organization: Planetary Data, Incorporated
>To: address@hidden
>Subject: Replacement character list limitation?

The above message contained the following:

> Steve, Steve, et al.,
> 
> On the replacement characters . . . am I missing something, or is there a 
> limitation of nine fields that can be specified via the "\<digit>" string.
> 
> For instance, if I have:
> 
> WMO   ^(..)(..)(..) (....) (..)(..)(..)/(.) (...) (....) (..)
>       FILE    -close  data/\1\2\3_\4_\6_\6\5\7_\8_\11_\10_\9
> 
> The "\11" and "\10" are recognized as "\1"1 and "\1"0 . . . do you see what I 
> mean?

I understand.  I suspect that the limit of nine such "back-references"
exists because the Unix Standard for regular expressions has just that
limit.  See, for example,

    http://www.opengroup.org/onlinepubs/007908799/xbd/re.html

I'll investigate whether this limit can be relaxed.

> Stonie Cooper,
> Planetary Data, Incorporated
> (402) 727-6599

Regards,
Steve Emmerson
LDM Developer