docs: caliper and xapi

Author: xchopin

docs/faq.md

@@ -18,3 +18,9 @@ var localTime = new Date(record.dateTime.getTime() + record.timeZoneOffset)
 The main entities are seperated in the bellow repositories, they are imported through the Maven `pom.xml` file
 - [xAPI and Caliper models (Events)](https://github.com/Apereo-Learning-Analytics-Initiative/lai-event)
 - [OneRoster and other models](https://github.com/Apereo-Learning-Analytics-Initiative/lai-model)
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+## Why xAPI statements are converted to IMS Caliper
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+Since we are using the OneRoster standard for our data model, Caliper is a natural fit as the event standard (both are designed by IMS Global). Use cases for the OpenLRW API are 100% education focused and IMS Caliper is an education specific standard (xAPI is more general purpose). Also many of the systems we integrate with (LMS such as Moodle, Canvas, etc) chose Caliper as their event standard.