The chart was owned by Association of Independent Radio Contractors (AIRC)the trade body for ILR stations. The chart was distributed by Satellite Media Services, produced by Capital Radio and compiled by the Media Research Information Bureau (MRIB). The chart differed from the entirely sales-based "official" Gallup chart (now the OCC) used by the BBC as it included airplay statistics when compiling the chart. In 1987, sales data for a Thursday-to-Wednesday week was logged manually in diaries by 300 record shops and posted to MRIB. In 1991, data was being collected from around 300 independent record shops who were provided with a checklist of currently released singles. Sales were "checked off against ticks on the retailers' masterbags" and these figures would be collected by telephone on Thursdays. Airplay statistics were factored in by all Independent Local Radio stations providing which playlist (A, B, or C) the current releases were on. More weight was given to the larger stations at the time, such as Capital (17 percent), BRMB, Clyde, GWR, Metro, and Piccadilly. If a record was on every Independent Local Radio station's A list the sales were boosted by 40 percent.