A type system for Excel needs to emulate some of the features found in languages which support a robust code validation system. The obvious differences between Excel and a formal programming language mean these validation features need to be adapted to work in Excel. For example, in a language based on a list of statements in a text file scopes are defined by the use of start/end delimiter pairs such as ‘{‘ and ‘}’ while Excel is grid of values with no natural scope. A scope might be a column or row of cells but it might be a collection of one or more cell ranges. This article will review the required features and how they can be used in Excel.