The FPI Attribute Type is a data type defined by XHTML Modularisation 1.1, declared in the DTD as XML 1.0 type CDATA.
Reference: *W3C - XHTML Modularisation 1.1 - Attribute Types
There are no Common Attributes with type FPI.
An SGML Formal Public Identifier
In XHTML 1.1, the only attribute with type FPI is
version, declared on the
html element and
having the #FIXED value "-//W3C//DTD XHTML 1.1//EN".