Fluidinfo offers a wide range of possible values for tags. These can be divided into two categories: primitive and opaque.
These are values that Fluidinfo understands natively, and which you can most usefully query on. The full list is as follows:
You can store any kind of information you like in an opaque tag value. Each such tag on an object has type information in the form of a MIME type. Because Fluidinfo treats these tags as opaque values, you cannot perform any search querying on them, apart from using has and except to select or exclude objects with opaque tag values. This applies even to opaque tags with types like text/plain. Even though such a tag probably holds a string, Fluidinfo will still treat it opaquely. If you want to pass a string and have it treated as such, i.e., for text indexing or equality comparisons, pass it as a primitive value.
Fluidinfo allows you to specify any MIME type information you like - including types you invent for your own purposes. When you add a tag with a specific MIME type to an object, Fluidinfo remembers the type and returns it when the tag is later requested. To give some examples, you could add a tag to an object with type application/pdf or audio/mp3 or your own my-app/preferences.
When using the Fluidinfo REST API, type information is transmitted in the HTTP Content-Type header.