It is not possible to determine whether a statement
is infallible based on the type of document it is. Infallible
statements can be made in a wide variety of documents,
but there has never been a document which has always
carried the charism of infallibility. Nor is there specific
language that the Pope has to use to indicate infallibility,
although they tend to use something of the form of:
[or I] declare by virtue of our apostolic authority . . .
A good discussion of the four characteristics of an
infallible teaching is in the EWTN document:
This specifically discusses the document Ordinatio
which infallibly declared that women cannot be ordained,
and it does an excellent job of discussing the principles.
EWTN also has other documents on the subject; go to:
search on keyword "infallibility".
It is extremely unlikely that this upcoming document
contains any new infallible teachings. It is intended
as an exhortation and meditation, which is not a typical
opportunity to make infallible statements.
Infallible statements are exceedingly rare. John Paul
made only two of them:
- one in the Apostolic Letter Ordinatio Sacerdotalis, pertaining to women's ordination, and
- one in the encyclical Veritatis Splendor, regarding abortion.
Before that, you have to go back to the 1950s to find
one (the Assumption).
Side note to Mary Ann's replied:
Infallible statements don't explicitly say they are
infallible, although you can tell by the way they are
written; for example, they usually:
- say they are defining
or declaring something
- they invoke Petrine authority
- they are addressed to the whole Church, and so forth.
Hope this helps,