Save _DIRECTORY as Field in Tag - Tag view

Is there a way to save _DIRECTORY as default field when using the Convert -> Tag - Tag menu? I currently have to enter this manually each time I use it, and it would be really useful if this could be saved as the default field for this function.

AFAIK none of the variables starting with an underscore can be selected from the field list.
The Convert>tag-tag function is the same as an action of the type "Format value". So if you have a pattern that you frequently want to apply to _FILENAME, it may be worthwhile to create an action to do that.