Although this is a string attribute, it may often be useful to store numerical values here, encoded as a character string, and to use these as data within the transformation function. Note, however, that this mechanism is not suitable for transferring large amounts of data (more than about 1000 characters) to an IntraMap. For that purpose, global variables are recommended, although the IntraFlag value can be used to supplement this approach. The default IntraFlag value is an empty string.
AST A Library for Handling World Coordinate Systems in Astronomy