Some concepts

A Client is the organization which uses the OMS. In v2.00 a Client can have only one User. One of the upgrades of v2.10 will be that a client can have several users who can share Groups and Respondents.
A User is an actual person - who has to have at least a Foundation Level registration at aMI - who uses the system
A Candidate is a person who is the 'subject' for the questionnaire. The Candidate record is kept in a separate database from all other OMS data. It stores the data which most obviously will not change over time, and which can identify the person: name, adress, email, gender, year of birth. In all cases at least one Respondent-record is connected to a Candidate.
A Respondent is, as it were, a Candidate with an instance of a MIDAS profile connected to it. The Respondent-record has all the data on a particular MIDAS profile.
A Reseller is an advanced user, who is responsible for the financial administration. Every Client is associated with a Reseller. The Client receives the invoices from this Reseller. In the Netherlands the Reseller is TweeMC B.V. An alias for Reseller in the OMS is ‘Provider’.