- /** Number of bytes that are going to be written for all the
- * streams combined. This is the amount in uncompressed data.
- * (The actual number of bytes will be less if the data is being
- * written compressed.) */
+ /** Total number of uncompressed bytes of stream data being
+ * written. This can be thought of as the total uncompressed
+ * size of the files being archived, with some caveats. WIM
+ * files use single-instance streams, so the size provided here
+ * only counts distinct streams, except for the following
+ * exception: the size provided here may include the sizes of
+ * all newly added (e.g. with wimlib_add_image() streams,
+ * pending automatic de-duplication during the write operation
+ * itself. When each such stream de-duplication occurs, this
+ * number will be decreased by the size of the duplicate stream
+ * that need not be written.
+ *
+ * In the case of a wimlib_overwrite() that the library opted to
+ * perform in-place, both @p total_streams and @p total_bytes
+ * will only count the streams actually being written and not
+ * pre-existing streams in the WIM file. */