Export features question: Anchor text wrapping symbol

I am not sure what Anchor text wrapping symbol under Export ->, but feel it might be useful during export.

Can someone help me understand. The subtext of the feature states what to fill into the input fields i.e. symbol on left and and symbol at right side of anchor.

I learned an anchor is during export can have URL included in syntax: [Anchor text](siyuan://blocks/block-id). Does Anchor text wrapping symbol allow to change this format kinda like a regular expression changer?

So from [Anchor text](siyuan://blocks/block-id) to [[Anchor text]](siyuan://blocks/block-id). This would obviously only work on document backlinks and not block backlinks I pressume.

As seen above I need a general explanation what it does