Note: According to the front flap of the first print edition of this novel:

Years ago, When House of Leaves was first being passed around, it was nothing more than a badly bundled heap of paper, parts of which would occasionally surface on the Internet.

Apparently this version is intended by the author to be the "1st Edition" of the work. The title pages of all print editions state "2nd Edition". The note goes on to say:

Now, for the first time, this astonishing novel is made available in book form, complete with the original colored words, vertical footnotes, and newly added second and third appendices.

The novel was also serialized on the iUniverse website from February 15 - March 17, 1999. See this article which explains the circumstances around the first print edition of the novel. In May 2006, a "Remastered Full-Color Edition" was published in both hardcover and trade paperbacks. The illustrations in the Appendices were in color. It probably continued the printing numbers of the first print edition, only striking out the "First Edition" statement of that edition.