Not used by any call.
Version of the characteristics set. Not to be confused with AttributeSystemVersion, which can be used to retrieve changes to attribute meta-data. In item-listing requests, if you specify the version of the attribute set that you have stored locally, eBay will compare it to the current version on the site and return a warning if the versions do not match. If an error occurs due to invalid attribute data, this warning can be useful to help determine if you might be sending outdated data. The current value of version is not necessarily "greater than" the previous value.
See the Field Index
to learn which calls use AttributeSetVersion.