According to Music Week another set of new rules are to be introduced into the way the main music sales charts are compiled. You'll remember, there has been quite some change in the charts system in the last year or so, primarily related to how and when digital music sales should be counted.
At the moment digital sales of singles tracks are counted, but only once a physical CD of that track is in the shops - ie if a track is available for download prior to physical release, those pre-physical release sales aren't counted. That will change next month, with pre-physical release sales counted the week before the physical release, so that in theory tracks could chart the Sunday before the physical CD single reaches record shops. Does any of that make sense? Ah well, it's not that important.
The other big change is that download sales of albums are to be incorporated into the albums chart for the first time next month.