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Message-ID:  <54037E00.9050005@latex-project.org>
Date:         Sun, 31 Aug 2014 21:56:48 +0200
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From: Frank Mittelbach <frank.mittelbach@LATEX-PROJECT.ORG>
Subject: Re: How to get l3str.sty, l3seq.sty, etc. these days?
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
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Status: R

Hi Michiel

> Let me put it like this. Until now, I've always been able to do this:
>
> \RequirePackage{expl3}
> \RequirePackage{l3prop}
>
> But now, this gives me the error message:
>
> ! LaTeX Error: File `l3prop.sty' not found.

correct. This is because we finally removed the individual .sty files.

Initially, during the first phases of expl3 (when new datatypes got 
added and a lot got changed or updated within those datatypes) it was 
useful to  have those as individual module files that could be loaded 
individually (and replaced for testing etc) but once things stabilized 
this became a problem as people loaded them in wrong order etc and we 
had to try to maintain all kind of dependency rules between the 
different files so that in the end normally most if not all of expl3 got 
loaded anyway.

Therefore we announced way back that one should always load expl3 and 
not any individual files.

and now we finally extract everything into a single file and the 
individual files only exist on the source level (just like LaTeX2e where 
you have many source files (.dtx) but only a single latex.ltx

So I guess you have to bite the bullet and remove the calls to 
individual files as it really don't make any sense to provide empty .sty 
files just to support the above scenario

regards
frank