1. In a system for creating and editing an electronic document, a method for converting a number between two systems of measurement, the method comprising: determining whether a string of text contained within the electronic document contains a number having an associated unit name; in response to determining that the string of text includes a number having an associated unit name, semantically labeling the number with schema information identifying the unit name as a source unit of measure; providing a list of actions that may be performed on the number to convert the number to a destination unit of measure, the list of actions identified based upon the schema information; receiving a selection of an action from the list of actions; and generating a converted number by converting the number from the source unit of measure to the destination unit of measure identified by the selected action.