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man/zip_source_read.mdoc

diff --git a/man/zip_source_read.mdoc b/man/zip_source_read.mdoc
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--- a/man/zip_source_read.mdoc
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 .Sh SYNOPSIS
 .In zip.h
 .Ft zip_int64_t
-.Fn zip_source_read "zip_source_t *zs" "void *data" "zip_uint64_t len"
+.Fn zip_source_read "zip_source_t *source" "void *data" "zip_uint64_t len"
 .Sh DESCRIPTION
 The function
 .Fn zip_source_read
 reads up to
 .Ar len
-bytes of data from the zip source
-.Ar zs
-at the current read offset and writes them to the buffer
+bytes of data from
+.Ar source
+at the current read offset into the buffer
 .Ar data .
+.Pp
+The zip source
+.Ar source
+has to be opened for reading by calling
+.Xr zip_source_open 3
+first.
 .Sh RETURN VALUES
 Upon successful completion the number of bytes read is returned.
 Otherwise, \-1 is returned and the error information in
-.Ar zs
+.Ar source
 is set to indicate the error.
 .Sh SEE ALSO
 .Xr libzip 3 ,