DSL Advances

The parameters, as defined in G.994.1, are generic and the data structure is used in all messages where parameters are communicated. The parameters have two types of classifications: NPars and SPars.

• NPars are parameters that have no subparameters associated with them.

• SPars are parameters that have subparameters with them.

Level 1 is the highest level in the tree, which contains an array of NPars and SPars. The general notation for parameters defined at Level 1 is NPar(1) and SPar(1). Each of the SPar(1) parameters have a set of NPars and SPars at Level 2, identified as NPar(2) and SPar(2) parameters, respectively. Because Level 3 is the lowest level in the three-level tree structure, there can be no SPar values at Level 3.

In Figure 5.5, the general notation is as follows :

• NPar(2) _j and SPar(2) _j indicate the set of Level 2 parameters associated with the j th Level 1 Spar.

• NPar(3) _j,k indicates the set of Level 3 parameters associated with the k th Level 2 Spar value(s), which is associated with the j th Level 1 SPar.