1. A memory for storing data for access by an application program being executed on a data processing system, the data related to a structural description of the spatial and parametric characteristics of an element and logical connections with other elements of a non-fixed layout document, comprising: a data structure stored in said memory, the data structure including information related to the non-fixed layout document; a plurality of assigned descriptions of logical connections with other elements, wherein the assigned descriptions of logical connections are represented as a hierarchical sequence of elements and are stored in the data structure; a plurality of assigned descriptions of spatial connections of the element, wherein the spatial connections relate to the other elements; a plurality of assigned descriptions of parametric characteristics of the element; an assigned algorithm for determining element search constraints; and an assigned set of parameters for identification of a compound element on the basis of aggregate constituents, wherein the compound element is made up of a combination of the element and a plurality of the other elements.