Editing Online codes (section)

===Decoding===
Obviously the decoder of the inner stage must hold check blocks which it cannot currently [[wikt:decode|decode]]. A check block can only be decoded when all but one of the blocks which it is attached to are known. The graph to the left shows the progress of an inner decoder. The x-axis plots the number of check blocks received and the dashed line shows the number of check blocks which cannot currently be used. This climbs almost linearly at first as many check blocks with degree &gt; 1 are received but unusable. At a certain point,  some of the check blocks are suddenly usable, resolving more blocks which then causes more check blocks to be usable. Very quickly the whole file can be decoded.

As the graph also shows the inner decoder falls just shy of decoding everything for a little while after having received ''n'' check blocks. The outer encoding ensures that a few elusive blocks from the inner decoder are not an issue, as the file can be recovered without them.