--modify feature allows you to cast a viewable field as a currency or binary

--modify=field1{...},field2{...}

You can apply the modification to the viewable (non-edit) display of the field using the --modify switch.

The currency syntax is --modify=cost{$},price{$}

Here, the cost and price fields will be displayed as wrapped in number_to_currency() when displayed on the list view and when displayed as show-only.

You can also use a binary modifier, which can apply to booleans, datetimes, times, dates or anything else. When using the binary modify, a specific value is displayed if the field is truthy and another one is display if the field is falsy.
You specify it using a pipe | character like so:

--modify=paid_at{paid|unpaid}

here, even though paid_at is a datetime field, it will display as-if it is a binary— showing either the truthy label or the falsy label depending on if paid_at is or is not null in the database. For all fields except booleans, this affects only the viewable output — what you see on the list page and on the edit page for show-only fields. For booleans, it affects those outputs as well as the normal edit output: The labels you specify are used as the labels for the radio buttons that the user can select.

You must separately specify these as show-only if you want them to be non-editable.

The available modifiers are:

modifier	what it does	can be used on
$	wraps output in number_to_currency()	float, integer
truthy label|falsy label	specify a binary switch with a pipe (|) character if the value is truthy, it will display as "truthy label" if the value is falsy, it will display as "falsy label"	boolean, datetime, date, time