Dates and Times

Each unique instant in SpreadsheetML time is represented as a distinct non-negative numeric serial value, which is made up of an integer date component and a fractional time component. As dates and times are numeric values, they can take part in arithmetic operations.

Numerous functions take as arguments one or more serial values or strings representing dates and/or times. Functions that care only about the date shall ignore any time information that is provided. Functions that care only about the time shall ignore any date information that is provided.