1. A computer-implemented method of risk factor scenario generation for use in a risk management application comprising: receiving user input at a scenario builder graphical user interface, wherein the user input identifies a plurality of risk factors affecting a portfolio under consideration; wherein each of said plurality of risk factors is an observable economic variable whose value or change in value translates into a change in the value of a portfolio under consideration, and wherein each of said plurality of risk factors is assigned to a risk factor class; creating a plurality of Block data structures; storing on a database said plurality of risk factors in said plurality of Block data structures such that each risk factor is stored in exactly one of the plurality of Block data structures, and such that risk factors stored in each Block data structure have similar statistical properties wherein risk factors with similar statistical properties are assigned to the same risk factor class; creating at least one Model data structure, each Model data structure comprising data defining how values of the risk factors with similar statistical properties change; building a Scenario Generator data structure, said Scenario Generator data structure comprising a calibrated model for generating risk factor scenarios; the calibrated model comprising a list of blocks and models associating a Model data structure with each of said plurality of Block data structures; and a codependent structure defining relationships between risk factors of said plurality of risk factors; creating a Scenario Set Definition data structure specifying how said Scenario Generator data structure is to apply to a user-specified risk management problem; generating a scenario set for said plurality of risk factors at a scenario engine server running on a machine to generate the scenario set by applying said Scenario Generator data structure, as specified by said Scenario Set Definition data structure, to a sampling of random numbers, wherein said generated scenario set comprises values of said plurality of risk factors at one or more future points in time; and producing one or more data files comprising data associated with said generated scenario set, for computing a monetary value associated with the portfolio under consideration.