Index: trunk/doc/user/07_io/io_easyeda/index.html
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--- trunk/doc/user/07_io/io_easyeda/index.html	(revision 10717)
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@@ -178,3 +178,22 @@
 symbol files within the same zip. The sheet file makes sense only together with
 the symbols, thus the whole (unpacked) zip is required.
 
+<H4 autotoc="yes"> How unzipping works </H4>
+<p>
+I decided not to introduce a libzip dependency, rather just call unzip as
+an external utility. Any zip implementation can be used as long as it
+provides two functionality:
+<ul>
+	<li> given a full path to a zip file, prints a file list to stdout (in whatever text format)
+	<li> given a full path to a zip file, extracts all files into the current working directory
+</ul>
+<p>
+For example on Debian-like systems the packgae <b>unzip</b> can do these.
+<p>
+The actual command lines for these two functions are configured, see
+config nodes <b>plugins/easyeda/zip_extract_cmd</b> and
+<b>plugins/easyeda/zip_list_cmd</b>; %s is substituted with the full path
+of the zip file and CWD is set before calling the extract command.
+<p>
+This is a weak dependency: any of these is required only if pro files are to
+be open.