Added a Glossary entry (with diagrams) explaining the difference in accuracy...

            </p>

          </definition>

          <definition name="Emission Angle">

          <definition name="Emission Angle"><a name="emission angle"></a>

            The emission angle (EMA) is the angle between the spacecraft and a

            vector drawn perpendicular to the planet's surface (surface normal).

            Using SPICE, ISIS applications compute this angle from the ellipsoid.

          </p>

          </definition>

          <definition name="Pixel Resolution">

          <definition name="Pixel Resolution"><a name="pixel_resolution"></a>

            The ground distance in meters from the left edge to the right edge

            of a pixel.

          </definition>

          <definition name="Line Resolution">

            The ground distance in meters from the top edge to the bottom edge

           <definition name="Oblique Pixel Resolution"><a name="oblique_pixel_resolution"></a>

            The ground distance (in meters) from the left edge to the right edge

            of a pixel.  This value is based on the <a href="#oblique_detector_resolution">oblique detector resolution</a>

            estimate, rather than the <a href="#detector_resolution">detector resolution</a> and is more accurate

            (particularly for off-nadir images).

          </definition>

          <definition name="Line Resolution"><a name="line_resolution"></a>

            The ground distance (in meters) from the top edge to the bottom edge

            of a pixel.

          </definition>

          <definition name="Sample Resolution">

            The ground distance in meters from the left edge to the right edge

          <definition name="Oblique Line Resolution"><a name="oblique_line_resolution"></a>

            The ground distance (in meters) from the top edge to the bottom edge

            of a pixel.  This value is based on the <a href="#oblique_detector_resolution">oblique detector resolution</a>

            estimate, rather than the <a href="#detector_resolution">detector resolution</a> and is more

            accurate (particularly for off-nadir images).

          </definition>

          <definition name="Sample Resolution"><a name="sample_resolution"></a>

            The ground distance (in meters) from the left edge to the right edge

            of a pixel.  

          </definition>

          <definition name="Detector Resolution">

            The size of the detector on the focal plane for each pixel.

          <definition name="Oblique Sample Resolution"><a name="oblique_sample_resolution"></a>

            The ground distance (in meters) from the left edge to the right edge

            of a pixel.  This value is based on the <a href="#oblique_detector_resolution">oblique detector resolution</a>

            estimate, rather than the <a href="#detector_resolution">detector resolution</a> and is more

            accurate (particularly for off-nadir images).

          </definition>

          <definition name="Detector Resolution"><a name="detector_resolution"></a>          

            The ground distance in meters from the left edge to the right edge of a detector.  If the 

	    lines and samples are not being summed and averaged, this value is equal to the pixel resolution.

            The formula for estimating this value works well if the image is taken near nadir, but 

            the accuracy falls off rapidly the farther off-nadir the image is taken.  For an estimate that 

	    handles off-nadir images with higher accuracy, one should use <a href="#oblique_detector_resolution">oblique detector resolution</a>.

          </definition>

          <definition name="Oblique Detector Resolution"><a name="oblique_detector_resolution"></a>

            This provides an improved estimate to the standard <a href="#detector_resolution">detector resolution</a> when the image is taken at an oblique 

            angle. It returns the square-root of the area of the projection of the detector onto the body of the target (in units of meters).

            If the image is taken at nadir, this is the ground distance between the left and right edge of the detector, because the 

            detector's projection is a square.  For off-nadir images, the projection has a trapezoidal shape.

            In Figure 1A below, an image of the Dufay X crater that was taken near nadir is displayed.  Figure 1B is a

            color map showing the relative difference between the oblique detector resolution, and the original detector resolution as a function

            of the emission angle.  For small emission angles (near nadir) the relative difference between the two estimates 

            is very small.  For larger emission angles (off-nadir), the relative difference between the 

            two estimates increases rapidly.  Figure 2A is an image of the Carlini crater group taken at an oblique angle.  Figure 2B is a color plot

            of the relative difference between the two estimates showing a minimum value of approximately 50% between the two when the 

            emission angles off-nadir are in the range 65-75 degrees.

		<table border = "1">

		<tr>

			<td>

			<center>

                                  <image width="496" height="496" src="assets/dufayx.png">

                                  <brief><br><strong>Fig 1A:</strong> A cropped view of Apollo image AS16-M-0025 centered on the Dufay X crater.  The spacecraft

                                  was very close to nadir when the image was taken.  </br>

                                  </brief>

                                  </image>

                        </center>

			</td>

                        <td>

			<center>

                                <image width="496" height="496" src="assets/carlini_craters.png">

                                <brief><br><strong>Fig 2A:</strong> A cropped view of Apollo image AS15-M-1556 centered on the Carlini crater group.

                                This photo was taken at an oblique angle.</br>

                                </brief>

                                </image>

                         </center>

		        </td>

		</tr>

		<tr>

			<td>

			 <center>

                                 <image width="584" height="492" src="assets/nadir40pct.png">

                                 <brief><br><strong>Fig 1B:</strong> Relative percentage difference between resolution estimates for</br>

                                 <br> a nadir image (see <strong>Fig. 1A</strong>).</br></brief>

                                 </image>

                         </center>

			</td>

			<td>

			<center>

                                <image width="582" height="492" src="assets/oblique40pct.png">

                                <brief><br><strong>Fig 2B:</strong> Relative percentage difference between resolution estimates for</br>

                                <br> an oblique image (see <strong>Fig. 2A</strong>).</br></brief>

                                </image>

                         </center>	

			</td>

		</tr>

                </table>				 

	  </definition>

          <definition name="I/F">