diff --git a/doc/src/region.rst b/doc/src/region.rst
index 94feee6ad4..6d4bbaca4b 100644
--- a/doc/src/region.rst
+++ b/doc/src/region.rst
@@ -46,6 +46,7 @@ Syntax
          xy = distance to tilt y in x direction (distance units)
          xz = distance to tilt z in x direction (distance units)
          yz = distance to tilt z in y direction (distance units)
+           xlo,xhi,ylo,yhi,zlo,zhi,xy,xz,yz can be a variable (see below)
        *sphere* args = x y z radius
          x,y,z = center of sphere (distance units)
          radius = radius of sphere (distance units)
@@ -211,7 +212,7 @@ and *ellipsoid* the x-, y-, and z- coordinates of the center of the
 sphere/ellipsoid can be specified as an equal-style variable.  And for
 style *cylinder* the two center positions c1 and c2 for the location of
 the cylinder axes can be specified as a equal-style variable.  For style
-*cone* all properties can be defined via equal-style variables.  For
+*cone* and *prism* all properties can be defined via equal-style variables.  For
 style *plane* the point can be defined via equal-style variables.
 
 If the value is a variable, it should be specified as v_name, where