Identifiers and attributes in DTO-Excel may be provided as either text or numeric data. Identifiers given in text cells are taken as-is subject only to the rules concerning case and “white space” insensitivity. Identifiers given in numeric cells are only accepted by the optimiser if they are integer (i.e. their fractional part is zero). Formulas that evaluate to either text or (integer) numeric data may also be used to specify identifiers in Excel.