I used to work for a music publishing company that supplied music to public libriaries. They do sell reasonably well although noticed that there would be piano reductions and Chords for most of the more straight pop stuff, for AC/DC or Iron Maiden, not attempt was made to provide a piano score, just a vocal melody line,and guitar chords. Most of the vocals always appeared to be on the same note however!!!!!...I did also see an attempt once to write out Iron Maiden guitar solos/riffs using a strange tablature rather than normal chord diagrams but this struck me as being a bit optimistic that anyone could follow them with sufficient skill to make at sound anything like the original. It litterally told you which string to use and where to place your finger on the the fretboard, which for a heavy hammer on type solo must be futile?