Revised the SparseMeasurementTile definitions to streamline. position scaling i…

…s no longer arbitrary.  It is hard-coded by the Tile Utilities to optimize precision for various linear and rotation coordinate frames.

@@ -88,8 +88,8 @@
         <comment>revision number</comment>
       </elem>
 
-      <elem name="datatype" multiplicity="1" type="ObservationType" >
-        <comment>The type of the observation data within the tile .</comment>
+      <elem name="reftype" multiplicity="1" type="RefPointType" >
+        <comment>The reference point type for the data stored within the tile. Tiles may only store one type of reference data.</comment>
       </elem>
       
       <elem name="status" type="TileStatus" multiplicity="1" >
@@ -142,25 +142,25 @@
       <struct name="Position" pack="true">
         <comment>Each position element represents the physical location of one or more measurements</comment>
         <elem name="x" type="Tensor.int24" multiplicity="1">
-          <comment>x component of the location of the tile data record</comment>
+          <comment>X component of the location of the tile data record.</comment>
         </elem>
         <elem name="y" type="Tensor.int24" multiplicity="1">
-          <comment>y component of the location of the tile data record</comment>
+          <comment>Y component of the location of the tile data record.</comment>
         </elem>
         <elem name="z" type="Tensor.int24" multiplicity="1">
-          <comment>z component of the location of the tile data record</comment>
+          <comment>Z component of the location of the tile data record.</comment>
         </elem>
         <elem name="ux" type="Tensor.uint8" multiplicity="1">
-          <comment>uncertainty of x component of the locations</comment>
+          <comment>Uncertainty of x component of the locations.</comment>
         </elem>
         <elem name="uy" type="Tensor.uint8" multiplicity="1">
-          <comment>uncertainty of y component of the locations</comment>
+          <comment>Uncertainty of y component of the locations.</comment>
         </elem>
         <elem name="uz" type="Tensor.uint8" multiplicity="1">
-          <comment>uncertainty of z component of the locations</comment>
+          <comment>Uncertainty of z component of the locations.</comment>
         </elem>
         <elem name="floor" type="Tensor.int8" multiplicity="1" default="0">
-          <comment> the floor number of the measurement record</comment>
+          <comment>The floor number of the measurement record.</comment>
         </elem>
 
       </struct>
@@ -195,12 +195,8 @@
         </comment>
       </elem>
 
-      <elem name="posUncertScale" type="Tensor.float32" multiplicity="1" default="1">
-        <comment>The scale of the location uncertainty in Position data.</comment>
-      </elem>
-
       <elem name="dataScale" type="Tensor.float32" multiplicity="1" default="1">
-        <comment>The scale of the measurement in measurement record.</comment>
+        <comment>The scale of the values in measurement record.</comment>
       </elem>
       
       <elem name="dataOffset" type="Tensor.float32" multiplicity="1" default="0">