A Fluidinfo user, for example named Sara, can tag as many different objects as she likes with her tags, using whatever values she likes. For example, she might tag an object representing The Eiffel Tower, with a sara/opinion of beautiful and another object representing Quantum Electrodynamics, with the sara/opinion of hard.
Each of an object’s tags has a type. The values for a tag do not have to be the same across all objects on which the tag appears. For example, there might be a numeric sara/opinion tag on one object, and a textual sara/opinion on another. She might normally rate books on a 0-5 scale, but also use some textual values, like “still reading”, “abandoned” or “can’t make up my mind”.
As another example, imagine a company storing resumes and putting a company.com/job-search/resume tag on a new Fluidinfo object for each job applicant. The tag could hold the submitted resume regardless of its document type. And because Fluidinfo offers an HTTP interface, the content of a tag could be viewed directly in a web browser, with Fluidinfo delivering the appropriate Content-type header for the tag.
Fluidinfo allows tags to hold numbers, text, images, spreadsheets, etc. — anything you want, in fact. You indicate the type of a tag when you create it, and Fluidinfo will give it back when the tag is later requested.
More details on possible tag values, are given in the advanced documentation.
The Fluidinfo permissions system specifies permissions for all occurrences of a tag on objects, not for tags occurrences on objects individually. So, for example, Sara can allow another user to read her sara/rating and sara/comment tags, prevent another from reading them, and can give a trusted friend permission to add those tags to new objects, or to change existing values. But she cannot give permission to someone to read the sara/comment tag on one object but not on another. I.e., the permission applies to the entire set of occurrences of sara/comment on objects.
There is no limit to the number of tags that can be attached to an object. For example, a book object might have sara/rating, sara/opinion, tim/opinion, and mike/opinion as well as many other tags holding information about title, price, number of stars, URLs, comments, page numbers that users are up to, dates that users read it, etc.
Any tag may be placed on any object. However, a particular tag, such as sara/opinion, cannot be present multiple times on an object. I.e., Sara cannot put two sara/opinion tags on the same object.
When a Fluidinfo tag is created, a description may be provided. There is a Fluidinfo object associated with the tag and the description simply becomes a tag on that object. As a result, it is also possible to search on tag descriptions using a regular Fluidinfo query.
