either
directly or indirectly. [ WFC: Entity Declared ] In a
document without any DTD, a document with only an internal
DTD subset which contains no parameter entity references,
or a document with "standalone='yes'", ... ... The
declaration of a parameter entity must precede any
reference to it... [ VC: Entity Declared ] In a document
with an external subset or external parameter entities with
"standalone='no'", ... ... The declaration of a parameter
entity must precede any reference to it... [ WFC: In DTD ]
Parameter-entity references may only appear in the DTD.
NOTE: misleading but this is handled. A PEReference may
have been detected in the current input stream the handling
is done accordingly to http://www.w3.org/TR/REC-xml#entproc
i.e. Included in literal in entity values Included as
 Parameter Entity reference within DTDs N)