The scale data structure is used to represent asymptotic scales (see MultiSeries for a definition).

A scale is represented as a table whose entries are:

The functions in the scale are represented using the global name _var with three arguments. Thus,  means that the function occurs in an expansion in the variable  at the point , and  is the expression of the function.

Scales being stored as tables, they can be extended during a computation.

Currently, only operations between multiseries expressed in the same scale are supported.