The real part of the acoustic propagation constant; neper per section, or unit distance.
"I just posted your company’s name in a blog about Robert Rheims’ Merry Christmas in Carols. Seems the Rheims family won’t allow a production of the album onto CD. Indirectly I pointed folks to you if they have a nice copy of the album. Your work on that record for me is just amazing. Thanks again so much."