+the WIM was being rebuilt (e.g. with \fB--rebuild\fR), in which case you should
+delete the temporary file left over.
+.PP
+\fISingle instancing\fR: The WIM format uses single-instance streams (roughly,
+"files"). When an image is exported, only the streams ("files") not already
+present in the destination WIM will be copied. However, a new copy of the
+image's metadata resource, which describes the full directory structure, will
+always be created.
+.PP
+\fIESD files\fR: wimlib v1.6.0 and later can export images from version 3584
+WIMs, which usually contain LZMS-compressed solid blocks and may carry the
+\fI.esd\fR file extension rather than \fI.wim\fR. However, \fI.esd\fR files
+downloaded directly by the Windows 8 web downloader have encrypted segments, and
+wimlib cannot export images from such files until they are first decrypted. In
+addition, to ensure the destination archive is created in the original WIM
+format rather than in the newer format, specify \fB--compress\fR=\fImaximum\fR.