Adobe Extending Flash Professional CS5 - Manual (Page 473)

451 EXTENDING FLASH PROFESSIONAL
Text object
Last updated 5/2/2011
text.variableName
Availability
Flash MX 2004.
Usage
text.variableName
Description
Property; a string that contains the name of the variable associated with the Text object. This property works only with
dynamic or input text; it generates a warning if used with other text types.
This property is supported only in ActionScript 1.0 and ActionScript 2.0.
Example
The following example sets the variable name of the selected text box to
firstName :
fl.getDocumentDOM().selection[0].variableName = "firstName";