"a" and "p" refer to the English words "Artist Proof", which refers to the version saved by the artist. A.P. version is often the version reserved by the artist before limited printing, and it is the work with the best printing quality and the writer's satisfaction.

Brock's concept of "artwork"

Modern art practice makes the concept of "artwork" wider and wider, which impacts the definition of various traditional artworks. Facing modern art, Brock, a famous American analytical aesthetician, redefines the concept of "artwork" from four aspects: the intention of artwork and people, the non-utility of artwork, artwork and artistic customs, and the open concept of artwork.

Art American economist Goldhaber pointed out: "If you measure the productivity of an artist in dollars, you will find that the most attractive artists make the most money." He believes that the purpose of art is to attract attention.

successfully attracting attention is the whole meaning of the existence of art. That is to say, in a sense, the decisive factor affecting the price of works of art is actually not only the artistic value of works of art itself and the number of works of art that exist in the world, but the attention that works of art can attract.