EPG-511 is Sky Sports Main Event SD, EPG-501 is Sky Sports Main Event HD.
EPG positions 501-510 are all Sky Sports HD, 511-519 are Sky Sports SD. 520 is Sky Sports Tennis HD.
This assumes you have a V6, as is the forum you've posted in. If you've converted yours to TV360, it's no longer a V6 and has the HD-swap - thus won't have EPG positions 511-519.
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