Tables can be present in a FitsChan as a result either of using the astPutTable (or astPutTables) method to store existing tables in the FitsChan, or of using the astWrite method to write a FrameSet to the FitsChan. For the later case, if the FitsChan "TabOK" attribute is positive and the FrameSet requires a look-up table to describe one or more axes, then the "-TAB" algorithm code described in FITS-WCS paper III is used and the table values are stored in the FitsChan in the form of a FitsTable object (see the documentation for the "TabOK" attribute).
AST A Library for Handling World Coordinate Systems in Astronomy