For the most part, IFR aircraft must be separated by 3 miles laterally or 1000 feet vertically. There are a few exceptions to this requirement. One exception is for simultaneous ILS approaches to parallel runways separated by at least 3600 feet. The requirements for these approaches is detailed in section 5-9-7. The key thing to remember is that aircraft must be provided standard IFR separation until they reach the appropriate capture box (described by the SOP). At LAX we can use simultaneous approaches between 24L/R and 25L/R; so you could have one aircraft on the ILS 24L and another on the ILS 25R; however, simultaneous approaches may not be used between two immediately adjacent runways. For example, you could not allow them between aircraft on the ILS 24R and ILS 24L since those runways are separated by much less than 3600’.