diff --git a/doc/tutorial.rst b/doc/tutorial.rst
index 7d544ec477235804da68576298d2bb4ddbe56a6a..29fab76e7af1d0a0dfa548a056a36273cf553b38 100644
--- a/doc/tutorial.rst
+++ b/doc/tutorial.rst
@@ -1064,6 +1064,29 @@ More complicated programs
 
 SCOP
 
+External Functions
+~~~~~~~~~~~~~~~~~~
+
+Loopy currently supports calls to several commonly used mathematical functions,
+e.g. exp/log, min/max, sin/cos/tan, sinh/cosh, abs, etc.  They may be used in
+a loopy kernel by simply calling them, e.g.::
+
+    knl = lp.make_kernel(
+            "{ [i]: 0<=i<n }",
+            """
+            for i
+                a[i] = sqrt(i)
+            end
+            """)
+
+Additionally, all functions of one variable are currently recognized during
+code-generation however additional implementation may be required for custom
+functions.  The full lists of available functions may be found in a the
+:class:`TargetBase` implementation (e.g. :class:`CudaTarget`)
+
+Custom user functions may be represented using the method described in :ref:`_functions`
+
+
 Data-dependent control flow
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/loopy/kernel/data.py b/loopy/kernel/data.py
index 463d10b4c9e06209f26261bb3ddf328520390e31..b1430448d1bcdb882345aa562132d2444e9641df 100644
--- a/loopy/kernel/data.py
+++ b/loopy/kernel/data.py
@@ -214,6 +214,7 @@ class KernelArgument(Record):
 
 
 class GlobalArg(ArrayBase, KernelArgument):
+    __doc__ = ArrayBase.__doc__
     min_target_axes = 0
     max_target_axes = 1
 
@@ -223,6 +224,7 @@ class GlobalArg(ArrayBase, KernelArgument):
 
 
 class ConstantArg(ArrayBase, KernelArgument):
+    __doc__ = ArrayBase.__doc__
     min_target_axes = 0
     max_target_axes = 1
 
@@ -232,6 +234,7 @@ class ConstantArg(ArrayBase, KernelArgument):
 
 
 class ImageArg(ArrayBase, KernelArgument):
+    __doc__ = ArrayBase.__doc__
     min_target_axes = 1
     max_target_axes = 3