"Purporting to be the writings of Abraham"

The header for the original 1842 printing of the Book of Abraham reads:

A TRANSLATION
Of some ancient Records that have fallen into our hands, from the Catecombs of Egypt, purporting to be the writings of Abraham, while he was in Egypt, called the BOOK OF ABRAHAM, written by his own hand, upon papyrus.

     First, we need not suppose that the word "translation" confines Joseph Smith to what is literally on the papyrus. It is well known that Joseph used the word "translation" in a much broader sense than we typically do today.
     Second, the word "purporting" indicates there is more going on than meets the eye. Here we have a situation where the words “purporting to be” are inserted to indicate something, yet the word “purporting” has negative connotations. That word was only used in the Times and Seasons in reference to things that had not been verified as true, and usually it was used as a means of denying the authenticity of the items in question.

     For instance, the December 1, 1842 edition contains the following excerpt, which uses the word to cast doubt on a “lost book,” which parallels the Book of Abraham:

We have lately seen a pamphlet, written, and published by James C. Brewster; purporting to be one of the lost books of Esdras; and to be written by the gift and power of God. We consider it a perfect humbug, and should not have noticed it, had it not been assiduously circulated, in several branches of the church.

     Another example (out of several which exist) is found in the September 2, 1844 edition:

Whereas Elders James J. Strang and Aaron Smith have been circulating a "revelation." (falsely called) purporting to have been received by Joseph Smith on the 18th of June, 1844: and through the influence of which they have attempted and are attempting to establish a stake, called Voree, in Wisconsin Territory, thereby leading the saints astray: therefore, the said James J. Strang and Aaron Smith are cut off from the church of Jesus Christ of Latter-day Saints, this 26th day of August, 1844.

     So, what should we make of the use of the word “purporting” in the Book of Abraham header? Well, we know Joseph is not trying to cast doubt on the authenticity of Abraham's writings which he translated. But he does seem to be casting doubt on the idea that the ancient records in his possession are themselves the plain writings of Abraham.