What does the reads per sequences mean

Question

[arronar]

Hi. I'm reading a paper and try to understand a plot of it. In the x-axis there is the position from promoter (bp) and in the y-axis it writes reads per 10^6 sequences.

What exactly that "reads per 10^6 sequences" means?

[WouterDeCoster]

That sounds indeed rather cryptic, perhaps you can add from which article this plot is?

[arronar]

here is the DOI of the article : doi:10.1038/nature09652

[WouterDeCoster]

Oh, that looks like normalized read count to me. Like FPKM but without taking transcript length into account (presumably not required for this).

[arronar]

Oh. thank you very much.