In the metadata tab of a specific field you can add metadata. Metadata types need to first be configured in the Settings page (see Settings - Metadata). In the following example, we save the code for "Gender" as it's used in the local electronic health record, which is "ZIS_GENDER". You can add as many metadata for a field as you want.
You can exclude the field data from all your data exports by setting this option to Yes in the Advanced tab of a field. In this case it will never get exported, irrespective of who is doing the export. The setting is by default to 'No'.
The Advanced tab will also allow you to encrypt a field if you are using the encryption module in your study.