Query: svn externals and export

Hi,

I'm creating our build scripts on a Windows machine for one of our
projects. The project includes some 'shared' code accessed through
svn:externals on the 'trunk' directory:

C:\tst>svn propget svn:externals http://locode01/svn/TAPS/trunk
PLPDF http://locode01/svn/PLPDF/tags/PLPDF_v204_sophos
Tools http://locode01/svn/OracleTools/trunk

The build script performs exports of specific directories above the
trunk so as to avoid 'unwanted' directories e.g. documentation, test
data, etc.

An export or checkout of the trunk will include the 'external'
directories, however I cannot export those directories individually by
name:

C:\tst>svn export http://locode01/svn/TAPS/trunk/PLPDF PLPDF
svn: URL 'http://locode01/svn/TAPS/trunk/PLPDF' doesn't exist

C:\tst>svn --version
svn, version 1.6.1 (r37116)
   compiled Apr 9 2009, 14:52:44

Is this the expected behaviour? If so, how should I construct a build
script to cope with this - with the consideration that I may not know of
future use of 'externals' e.g. the 'wibble' directory becoming
externally referenced at some unknown time.

-- 
Andy 
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