1. A method in a computer system for modifying at least one compressed element chunk in a main storage area, comprising: storing at least one root storage in the main storage area; storing a model directory in said at least one root storage; storing at least one model including a graphic element list and a control element list in each model directory; storing at least one compressed element chunk in each graphic element list and control element list, wherein each said compressed element chunk comprises compressed elements; storing said at least one root storage in a temporary memory; storing in said at least one of root storage a control model containing a control model header, a global control element list and a global graphic element list, wherein said global control element list and said global graphic element list contain element chunks including global elements, wherein said global elements are accessed for use in any model directory; associating a header with each root storage; storing in said at least one root storage at least one of a first stream containing a header, a second stream containing session information, a third stream containing a manifest and a fourth stream containing file properties; decompressing said compressed element chunks and compressed elements in said graphic element list and said control element list; modifying elements in the temporary memory; flagging said decompressed element chunks having said modified elements in said temporary memory with a dirty flag; compressing said flagged element chunks to provide modified compressed element chunks after a predetermined idle time has passed; and replacing said compressed element chunks in the main storage area with said modified compressed element chunks.