The Entity Filter may be the most powerful thing built for Pushword.
It's offer to apply what you want on properties from a class (mostly entity and often mostly Page).
It can be called from PHP (from Pushword\Core\Component\EntityFilter\Manager) or directly in Twig template file (with pw function).
It's permit, for example, to render markdown in title : {{ pw(page).title|raw }} for title being Page **title** will render Page <strong>Title</strong> if markdown filter is configured for string or for title in pushword.filters or directly in the app.filters (see configuration).
Each entity (mostly Page) can override one or multiple just setting filter_*filterName*: false in customProperties. See for this page, twig is disabled.
You can find the list of avalaible filters in core/Component/EntityFilter/Filter.
You can easily create a new filter implementing Pushword\Core\Component\EntityFilter\Filter\FilterInterface.
For now, filter are partially autowired with current App, current Manager, Twig and the current entity.
See Pushword\Core\Component\EntityFilter\Manager::getFilterClass and ...\Filter\Required***Trait.php.
You can easily create an extension wich add special action after filtering based on entity_filter.after_filtering event wich contain Manager and string property.