1. A method for establishing a mapping between internal metadata and external metadata within a report design environment, the method comprising: reading, by a computer system, metadata from a database that describes data stored in the database to create the internal metadata within the report design environment; presenting, by the computer system, the internal metadata within a report layout visual design area of the report design environment as a set of data points within a grid having row and/or column headings determined by dimensional metadata from the internal metadata; receiving, by the computer system, a first selection of a portion of the grid; determining, by the computer system, whether external metadata describing all data points within said first selection is predefined; presenting a list of predefined metadata based on determining that the external metadata describing all data points within said first selection is predefined; determining, by the computer system, whether a syntax of external metadata describing all data points within said first selection is predefined based on determining that the external metadata for said first selection is not predefine; requesting, by the computer system, a specification of external metadata to be created based on determining that the syntax of external metadata describing all data points within said first selection is predefined based on determining that neither external metadata describing all data points within said first selection is predefined nor a syntax of external metadata describing all data points within said first selection is predefined: creating, by the computer system, new internal metadata as a new row or column in the grid, receiving, by the computer system, a formula involving one or more data points within the first selection, configuring, by the computer system, a cell in one of the new row or column of the grid with the formula involving the one or more data points within the first selection and creating, by the computer system, a mapping between the internal metadata represented by the set of data points within the grid and the external metadata selected or specified for data points within the first selection.