and to prevent searches, there are two vectors of pointers, one

associated with FIDV and the other with VIDV. The form of both vectors

(VIPV and FIPV) is the same, and they will be described together. As

usual the first word is the length of the data in the vector. The

second word is a pointer to the first FIDV or VIDV cell, the third word

is a pointer to the second cell, etc. The entire data structure as

described so far fits together in the fashion illustrated in Fig. 5-3.

 Satellite data structures to the index representation data

structures are the vectors "IDMPV," the Index Display Matrix Pointer

Vector, and "IDL," the Index Decision List. The vector IDMPV is

accessed through VIDV and merely provides the name of the Index Display

Matrix for each of the variable indices in VIDV. The name is not stored

in VIDV because that would complicate searching through the Index

Display Matrix should that be necessary. The index decision list is

the vector which contains the index decision declarations. Index

decisions are offsets either from the lower or upper limit of the

function index. Each function index has associated with it an IDL cell

which is composed of two sub-cells, as shown in Fig. 5-4. If a function

index has no index decisions, its IDL cell will have no entries. Each

IDL cell has three length specifications, the first stating the length

of the entire cell. The other specifies the length of each of the sub-

cells. The first sub-cell, the L offset sub-cell, specifies the offsets

of decisions from the function index lower limit, and the second

specifies the offsets of decisions from the function index upper limit.

The index decisions can be declared in two ways; either the user can

declare them or algorithms can assign them. Declared decision variables

can never be changed, while derived decisions can be changed. In order