Both Tag editors in Helium supports tagging with dynamic contents.
This means that you can take advantage of the Tag to filename engine to generate aggregated custom formatted content, useful for example when populating custom fields.
Below follows an example:
1) In the field Custom 1, enter {{album}} - {{title}}
2) Apply the content to all files using the Apply function (Tag editor) or lock the field in the Advanced tag editor.
3) Save/Apply the changes.
What Helium will do now is:
1) Perform a pass where the static tags are applied
2) Perform a second pass where the dynamic contents are generated from the data stored in step one above
This function is a powerful complement to do post processing of data like appending a static text to another field, aggregating contents of fields and much more.