Net Capacity is a physical measurement of a school's buildings and facilities. This equates to the total number of pupils
that it is deemed the school can theoretically hold. (It's always interesting to compare the net capacity with the NOR - the total number of pupils actually on roll. It's harder for the school to complain about overcrowding in corridors and communal areas if the Number on Roll is in fact less than the Net Capacity.)
From the net capacity is derived the IAN (Indicated Admission Number) for the number of pupils each year group can accommodate. This is again a theoretical number, and can be modified by agreement if there is a good reason. The actual admission number is then called the PAN (Published Admission Number).
For example, a school might have an IAN of 177. However, the admission authority could decide that 6 classes of 30 would make more sense, and settle for a PAN of 180.
It's usually a good idea to compare the IAN and PAN, and - if there's a significant difference - ask at stage 1 of an appeal for an explanation.
If the PAN is lower than the IAN, it suggests that there is room in the year group for more pupils.
http://www.elevenplusexams.co.uk/11plus ... rs.php#c13
http://www.elevenplusexams.co.uk/11plus ... rs.php#c14
These are 'stage 1 matters', and, as I've written elsewhere, most cases tend to be won or lost at stage 2 when parents give their reasons for wanting a place.