A Text Boundary defines an area WITHIN the Print Area in which the text can appear. It is defined using the X and Y coordinates system in the same way that an Image Area is defined by. For example X and Y denote the top-left corner of the boundary. To set this simply edit your text area an access the "Advanced" menu shown below. 

The X Pos and Y Pos values for the text area still control the position of the text and should be set within the confines of the text boundary. If not, the text will be invisible as the text boundary crops anything outside of its border on-screen.

There are additional options available within the Text Boundary menu; Auto Fit (single line only), Auto Newline (multi line only), Auto Arc (single line only), Auto Wrap (single line only), Preview Clip and Artwork Clip as seen below. 

Below we have defined the differences between the different boundary options. 

1. Auto-fit - Auto Fit (single line only) automatically rescales the font size when the input text reaches the specified Text Boundary. It is context sensitive - it will only function if the Multiline facility is DISABLED.
   
2. Auto-newline - Auto Newline (multi line only) automatically adds a new line when the input text reaches the specified Text Boundary.  This feature is based on the entered word spacing and is context sensitive - it will only function if the Multiline facility is ENABLED.
   
3. Auto-arc - Auto arc can used to automatically bend text around the circumference of a circle based on the dimensions of the text boundary. Note that the width and height of the boundary should be identical to create a square for this feature to work correctly.  The direction of the text can be controlled with the arc direction drop-down in the main text area settings.  Note that the auto-arc feature does not work with multi-line text.
   
4. Clip in Artwork - When enabled this option will also clip text in the print output at the border of the text boundary. This option is supported with Raster and Vector PDF output types only.

If you are experiencing clipping of the font at the text boundary, simply turn off 'Enabled', autofit, newline and arc only require the co-ordinates and size of the text boundary need to be specified.