There are several ways to set custom data in Fullstory. Each of them can take a unique set of properties. For instance, a custom field is one that you define that Fullstory saves, displays, and that can be used in search.
Note: Server and Browser API custom data properties no longer require type suffixes, but Mobile APIs still require them. More information about type suffixes can be found here.
Learn more about common troubleshooting tips for custom user data.