[ownedbycats]

If you want to see an example of the Calibre template language in action, here's one I use:

program:

## Splitting tags
	if 
		'^(Fiction|Nonfiction|Magazines & Periodicals)' in $#booktype 
	then 
		split_tags = re($tags, '\.', ',') 
	else
		split_tags = ''
	fi;

## Removing a few unwanteds and sorting
	cleaned_tags = list_sort(list_difference(
		split_tags,
		'[Cleanup], Fiction, Nonfiction, Magazines & Periodicals, Cultures & Regions, Social Issues',
		','), 0, ',');

## Adds 'Omnibus' if present in #admintags
	if 
		'omnibus' 
	in 
		$#admintags 
	then 
		cleaned_tags  = 'Omnibus' & if cleaned_tags then ', ' & cleaned_tags fi
	fi;

	cleaned_tags

This does several things:

1. If the custom column #booktype is set to Fiction, Nonfiction, or Magazines & Periodicals, it 'splits' the tag at the periods. Fiction.Science Fiction becomes Fiction, Science Fiction. If a book doesn't have one of the defined entries in #booktype, it returns an empty value (to prevent template errors).

2. It then removes a number of selected entries from the tags and sorts the remaining results.

3. Lastly, if 'omnibus' is present in custom column #admintags, it adds Omnibus to the beginning of the string.

Originally Posted by Sunshine82

It might be easier to explain what I am looking to accomplish in order to determine whether it is possible or if there is another way of accomplishing my goal. I am wondering if it's possible to pre-program the customized column I created entitled Genre with a comprehensive list of possible entries in advance; if so, this would allow me to create the hierarchy tree ahead of time before then assigning the designated genre path to particular books. [I have attached a screenshot to provide context.]

Take a look at the Tag Mapper.