eBay Item Specifics
To use eBay Item Specifics:
1) Enable the Item Specific(s) you wish to use (or create your own custom Item Specific). This is done via Attribute Mapping mode (accessed either from the Home screen or from the mode selector on the Listings screen).
Make sure you are on the eBay site you are wishing to edit by using the drop down at the top right. Navigate to Item Specifics and expand the rows. The attribute mapping screen will show all the possibilities for ALL the categories of all your items on eBay. This list can be long due to how many eBay suggest and will vary depending on how varied your product catalog is. At the bottom of the list you can create your own custom Item Specific.
Item Specifics required or recommended by eBay will show with an asterisk next to them.
The reason you have to first enable is because most item Item Specifics suggested by eBay aren't used and simply adding them to the multi-edit grid as additional columns would be unwieldy.
2) Set the value for the enabled Item Specific
The default value once enabled is "Codisto Grid". That means you can edit in multi-edit mode as a column on the grid.
It's also possible to map an attribute value at this point (or edit via the single edit mode).
3) Save via the green button, top left
4) To edit Item Specifics via multi-edit mode you need to add the relevant columns to the grid that you wish to edit. You can add or remove columns to make use easier by clicking on 'Extra fields'
Scroll right on the grid and expand the Item Specifics column group and edit either individually or in bulk (using filters if necessary).
Then save using the white eBay button at the top left.