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Date:         Sat, 7 Aug 2010 15:57:03 +0200
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From: Arno Trautmann <Arno.Trautmann@GMX.DE>
Subject: optional (#1:#2) with xparse
To: LATEX-L@listserv.uni-heidelberg.de
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Status: R

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Hi all,

I am looking for a way to define an environment that takes a range as an
optional argument. This should be given in the following way:

\begin{environment}(15:5.23)

with a default value, say (1:3). The two limits should then be parsed as
single arguments which are separated by the colon.
I am trying to do this with xparse and got some possible solutions with
the u and d argument type, but I didn=E2=80=99t manage to get the parenth=
eses
optional. I guess what I need is some kind of an optional u argument =E2=80=
=A6

Does anyone have a suggestion how to easily implement these requests?

cheers
Arno


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