File Size

File sizes are required for e-books and other digital products. Providing information on file sizes is intended to inform customers but also booksellers about the transfer volume. This information is of particular interest for mobile use by customers.

The file size is expressed in the extent composite using code 22 for the ExtentType or b218. The unit used for the file size is listed in ExtentUnit or b220. The following values from code list 24 can be used here.

Code Unity
17 Bytes
18 Kbytes
19 Mbytes

Please note: all file sizes are translated by Metabooks into kilobytes.

A product with a file size of 5,000 kilobytes thus looks as follows.

ONIX 3.0 Short
<extent>
  <b218>22</b218> 
  <b219>5000</b219>
  <b220>18</b220> 
</extent>
ONIX 3.0 Reference
<Extent>
  <ExtentType>22</ExtentType>
  <ExtentValue>5000</ExtentValue>
  <ExtentUnit>18</ExtentUnit>
</Extent>