From Camp 2011 Public Wiki

The datatype text is used for texts of arbitrary length. Text is thus very similar to Type:String, but without the length restriction of the latter. The price for this additional freedom is that it is not possible to use specific values of Type:Text in semantic queries, or to sort query results by such values (the only exception is the interactive sorting of tables using the sort icon in the column header).

Besides this, the same rules as for Type:String apply for Type:text values as well.

This type is among the standard datatypes of this wiki.