This would be the FeedZ that you enter when you create a tool and set it's speeds and feeds.
To make the work, you need to have your post recognize this value. This is done by using the "feedz" variable in your post. Here is an example:
*APPROACH*
N"lnbr" G01"x""y""z"F"feedz"
*END_SECTION*
Hope this helps,
Dan