Application program interfaces (API) are provided for labeling strings while a user is creating a document and providing user actions based on the type of semantic label applied to the string. A recognizer API is provided and includes properties and methods or instructions which allow recognizer plug-ins to semantically label strings of text or cells or information. An action API is provided and includes properties and methods that are called upon when a user initiates particular actions such as opening a web browser, going to a particular URL, or opening an instance of a word processing or spreadsheet program. After the strings are annotated with a type label, application program modules may use the type label to provide users with a choice of actions. If the user's computer does not have any actions associated with a type label, the user may be provided with the option to surf to a download Uniform Resource Locator (URL) and download action plug-ins for that type label. One or more recognizer plug-ins perform the recognition of particular strings in an electronic document. The recognizer plug-ins may be packaged with an application program module or they may be written by third parties to recognize particular strings that are of interest. One or more action plug-ins provide possible actions to be presented to the user based upon the type label associated with the string.