Delivery Frameworks (aka HDx) is an advanced feature of Realizeit that provides an institution with complete UI and UX controls over the lesson experience.
In general, lesson files created using the authoring tool consist of HTML. When these files are being used for a lesson, they are combined with Cascading Style Sheets (CSS) and JavaScript (JS) built and maintained by Realizeit. This provides the familiar lesson experience. Delivery Frameworks allow the institution to supply their own CSS, JS or other files that instead control the styling and interactivity of the lesson. This can include any interactive components the institution might want to employ. It should be noted that when using this feature the institution becomes responsible for the usability and accessibility of the lessons.
The standard lesson experience is the default. However, Realizeit can provide a sample delivery framework to an institution which can be employed and/or adjusted.