A critical distinction to understand in Labmatrix is the distinction between a Person and a Subject, a distinction that reflects the difference between a human being's properties (e.g., name, demographics) and the properties related to that human's participation in a study (e.g., the start date of the participation, their custom ID on the study). The distinction allows Labmatrix to enforce access limitations so that study data is only visible to that study's users, yet the general information about NIH patients is visible to the entire NIH community. Below is a simplified diagram showing the relationship of the two; the green area is the Person and associated data, and the yellow area is the Subject and associated data.
The notion of a Person reflects the information which specifically describes a human being's properties – things such as name, date of birth, gender, race, ethnicity, and medical record numbers. This is the part of the above diagram in the green box; you'll note the small "Race" and "Medical Record Number" boxes, which indicate that a single Person might have more than one of these (e.g., multi-racial, or different MRNs at different institutions).
The notion of a Subject is what connects a Person to a study – e.g., the Person named "John Doe" is participating on a study named "Cancer Stem Cells", so that Person has a Subject record which links him to the Study. The easiest way to remember this distinction is by remembering that any one human being can participate in more than one study – for example, the person John Doe might be participating in a Derm Branch study, a Radiation Oncology Branch study, and a Surgery Branch study.
There is still only one human being, so there's only one Person record, but there are multiple Subject records linked to that Person which each represent the person enrolled on a specific study. The entire NCI can access that one Person record, but only those people with permissions to access each individual study can access each individual Subject record and the data that's linked to it. (So in the above diagram, each yellow box represents a separate access group, and the data within each is only accessible to those users with the proper permissions on that study.)
In Labmatrix, if you're viewing a Subject record, there will be a gray box near the top of the record with the information about the Person, and then a link within the record that lets you bring up the Person record itself. If you're viewing a Person record, then there's a tab that will list all the Subjects for that one Person.