Updated documentation

docs/source/usersguide/input.rst

@@ -1170,7 +1170,7 @@ implemented in openMC:
 ``<plot>`` Element
 ------------------
 
-Each plot must contain a combination of the following attributes or
+Each plot is specified by a combination of the following attributes or
 sub-elements:
 
   :id:
@@ -1191,6 +1191,18 @@ sub-elements:
 
     *Default*: ``cell``
 
+  :level:
+    Universe depth to plot at (optional).  This parameter controls how many
+    universe levels deep to pull cell and material ids from when setting plot
+    colors.  If a given location does not have as many levels as specified,
+    colors will be taken from the lowest level at that lcation. For example, if
+    ``level`` is set to zero colors will be taken from top-level (universe zero)
+    cells only.  However, if ``level`` is set to 1 colors will be taken from
+    cells in universes that fill top-level fill-cells, and from top-level cells
+    that contain materials.
+
+    *Default*: Whatever the deepest universe is in the model
+
   :origin:
     Specifies the (x,y,z) coordinate of the center of the plot.  Should be three
     floats separated by spaces.

src/relaxng/plots.rnc

@@ -7,6 +7,7 @@ element plots {
       attribute type { "slice" | "voxel" })? &
     (element color { ( "cell" | "mat" | "material" ) } |
       attribute color { ( "cell" | "mat" | "material" ) })? &
+    (element level { xsd:int } | attribute level { xsd:int })? &
     (element origin { list { xsd:double+ } } |
       attribute origin { list { xsd:double+ } })? &
     (element width { list { xsd:double+ } } |