In the real world, where people exchange files (on their hard drives, in USB sticks, as email attachments, etc.), a file suffix is often enough to distinguish what kind of data is being exchanged. However, DNAnexus operates on other, more complex, structures such record objects. To aid users and developers in establishing standards for data representation, DNAnexus provides a very simple type API. A type is a word (of length at least 1) consisting of characters in the ASCII range 47-57, 65-90, 95, 97-122 (that is, 0-9, A-Z, a-z, / and _), such as "UploadSentinel" or "history-record". In the DNAnexus platform, objects can be marked as being conformant to one or more types. This type system is advisory; types are semantically defined using free-form text, and object-type conformance is not checked by the system.