It is the feature sets that define whether it is a full OIS or reduced functionality of Desktop. Tracking back to history, MOSAIQ Desktop was created for developing market that are not ready to take on full OIS functionality and to avoid relative high initial investment.
This is especially true for Asia, and you do not find Desktop in US, Australia etc.
MOSAIQ Desktop was also intended to replace Elekta linacs’ legacy R&V i.e. Premium Therapy during the transition period where the main objective is to provide a new R&V with better future, but full OIS functionality was not intended.
To answer the second part of the questions, yes, it is the transition from Desktop to OIS. However, please note MRT13321 is a zero price item just to define the nature of offer. In the process, we need to ‘equip’ the Desktop with additional features so to qualify it to be full OIS. Individual item such as document management will be added if not already exist in the Desktop.
I hope this helps.