| `VisitAssessors` | Columns storing identifiers for the assessors that administered a(n academic study's) participant measurement session (i.e. visit to the research center). | Automatically kept synchronized with environment configuration. |
| `WatchData` | Columns containing data collected by wearable devices | Managed by Data Administrator. |
# Step by step
Several parties are involved in determining PEP's data structure.
Column management:
- Some of PEP's columns are predefined and automatically created when a PEP environment is provisioned.
- The PEP (support) team manages an environment's basic configuration. Short pseudonym columns are created (and removed) as a result.
- Data Administrator can create and remove columns by means of [the `pepcli ama column` command](Using-pepcli#ama-column).
Row management:
- Users with [write access](Access-control#data-access]) determine the row(s) into which they store data.
- When specifying an existing [identifier](Pseudonymization#identifiers-in-pep), data are stored in the specified row.
- When specifying a new (i.e. previously unknown) identifier, data are stored in a new row.
Column and row grouping:
- The contents of some column groups depend on environment configuration. These column groups are automatically updated by the PEP system.
- Other column groups are managed by Data Administrator using the [`pepcli ama columnGroup`](Using-pepcli#ama-columngroup) and [`pepcli ama column`](Using-pepcli#ama-column) commands.
- Row groups are managed by Data Administrator @@@ link to pepcli command @@@.
