<layer name="reading">

The reading layer provides data to be displayed by a gauge widget. The reading layer is required if column names are used in the reading_ attribute of <widget class_="gauge">, or if the reading_ attribute is omitted altogether. (Available as of prod-9)

Inside the <layer> tags, a query that returns the column names passed to the reading_ attribute must be provided. The resultant columns from the query must be numeric. Only the first row of the worksheet returned by this query will be used.

If the reading_ attribute is omitted from <widget class_="gauge">, the number of columns resulting from the query associated with the <layer> must not exceed the value of the maxcols_ attribute, if it is specified

<dynamic>
  <widget class_="gauge">
    <layer name="reading">
      [1010data_QUERY]
    </layer>
  </widget>
</dynamic>

Example: <layer name="reading"> with reading_ attribute

<dynamic>
  <widget class_="gauge" type_="linear"
   base_="pub.demo.retail.item" title_="Total Units by Store"
   min_="0" max_="25" width_="300" major_="10" 
   colors_="purple,red,blue" reading_="m0,m1,m2" >
    <layer name="reading">
      <tabu label="Tabulation on Sales Item Detail" breaks="store">
        <tcol source="units" name="tot_units" 
         fun="cnt" label="Count"/>
      </tabu>
      <colord cols="tot_units"/>
      <transpose/>
    </layer>
  </widget>
</dynamic>

Example: <layer name="reading"> without reading_ attribute

<dynamic>
  <widget class_="gauge" base_="pub.demo.retail.item" 
   min_="0" max_="20" width_="300" electric_="1">
    <layer name="reading">
      <tabu label="Tabulation on Sales Item Detail" breaks="store">
        <tcol source="units" name="tot_units" 
         fun="cnt" label="Count"/>
      </tabu>
      <colord cols="tot_units"/>
      <transpose/>
    </layer>
  </widget>
</dynamic>