A tag is a variable used to connect data with templates, based on User choices.
Tags are combined in strings of either two or three tags, depending on the type of the connection.
Tag strings are used to connect User choices (e.g. in User Profiles/forms) to insertion of data in a template.
Examples of tag strings:
A tag string often starts with either "Profile" or "Form" or "System".
%Profile% indicating that data comes from the user profile.
%Form% indicating that data comes from a form assigned to the document.