UseDesc Field Removed in Products and Categories
Posted 9 Sept 2018, Doug DePrenger
Starting in version 10.8.0, in items and categories, the UseDesc has been removed as it causes confusion. It was used to signify whether the Description: field or Meta Description: field is to be used for the meta description.
Whatever is in the meta description field will be used for the meta description.
If the word 'blank' (no quotes) is the only word in the meta description field, the meta description will be published blank. If the (most) search engines see a bank entry, they will fill it in themselves.
If the Meta Description: field is left blank, the Description: field will be used. This is generally not a good idea.
References
meta description - this will tell you all you need to know about a meta description and why they are important.
***