document implementation requirements for invalid object checking (#842)

api/appendix_f.asciidoc

@@ -98,7 +98,7 @@ include::{generated}/api/version-notes/CL_INVALID_BUILD_OPTIONS.asciidoc[]
 | {CL_INVALID_COMMAND_QUEUE_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_COMMAND_QUEUE.asciidoc[]
-| Returned when the specified command queue is not a valid command queue.
+| Returned when the specified command queue is not a <<valid-object-definition,valid command queue>>.
 
 | {CL_INVALID_COMPILER_OPTIONS_anchor}
 
@@ -108,12 +108,12 @@ include::{generated}/api/version-notes/CL_INVALID_COMPILER_OPTIONS.asciidoc[]
 | {CL_INVALID_CONTEXT_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_CONTEXT.asciidoc[]
-| Returned when a specified context is not a valid context, or when mixing objects from multiple contexts.
+| Returned when a specified context is not a <<valid-object-definition,valid context>>, or when mixing objects from multiple contexts.
 
 | {CL_INVALID_DEVICE_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_DEVICE.asciidoc[]
-| Returned when a specified device is not valid.
+| Returned when a specified device is not a <<valid-object-definition,valid device>>.
 
 | {CL_INVALID_DEVICE_PARTITION_COUNT_anchor}
 
@@ -133,7 +133,7 @@ include::{generated}/api/version-notes/CL_INVALID_DEVICE_TYPE.asciidoc[]
 | {CL_INVALID_EVENT_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_EVENT.asciidoc[]
-| Returned when a specified event object is not a valid event object.
+| Returned when a specified event object is not a <<valid-object-definition,valid event object>>.
 
 | {CL_INVALID_EVENT_WAIT_LIST_anchor}
 
@@ -179,7 +179,7 @@ include::{generated}/api/version-notes/CL_INVALID_IMAGE_SIZE.asciidoc[]
 | {CL_INVALID_KERNEL_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_KERNEL.asciidoc[]
-| Returned when the specified kernel is not a valid kernel.
+| Returned when the specified kernel is not a <<valid-object-definition,valid kernel object>>.
 
 | {CL_INVALID_KERNEL_ARGS_anchor}
 
@@ -204,7 +204,7 @@ include::{generated}/api/version-notes/CL_INVALID_LINKER_OPTIONS.asciidoc[]
 | {CL_INVALID_MEM_OBJECT_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_MEM_OBJECT.asciidoc[]
-| Returned when a specified memory object is not a valid memory object.
+| Returned when a specified memory object is not a <<valid-object-definition,valid memory object>>.
 
 // This currently defined in cl.h, but it's not a core API error code.
 //| {CL_INVALID_MIP_LEVEL_anchor}
@@ -225,12 +225,12 @@ include::{generated}/api/version-notes/CL_INVALID_PIPE_SIZE.asciidoc[]
 | {CL_INVALID_PLATFORM_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_PLATFORM.asciidoc[]
-| Returned when the specified platform is not a valid platform.
+| Returned when the specified platform is not a <<valid-object-definition,valid platform>>.
 
 | {CL_INVALID_PROGRAM_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_PROGRAM.asciidoc[]
-| Returned when a specified program is not a valid program object.
+| Returned when a specified program is not a <<valid-object-definition,valid program object>>.
 
 | {CL_INVALID_PROGRAM_EXECUTABLE_anchor}
 
@@ -250,7 +250,7 @@ include::{generated}/api/version-notes/CL_INVALID_QUEUE_PROPERTIES.asciidoc[]
 | {CL_INVALID_SAMPLER_anchor}
 
 include::{generated}/api/version-notes/CL_INVALID_SAMPLER.asciidoc[]
-| Returned when a specified sampler is not a valid sampler object.
+| Returned when a specified sampler is not a <<valid-object-definition,valid sampler object>>.
 
 | {CL_INVALID_SPEC_ID_anchor}
 

api/glossary.asciidoc

@@ -799,6 +799,7 @@ Unit of execution ::
     host-thread), kernel-instance, host program, work-item or any other
     executable agent that advances the work associated with a program.
 
+[[valid-object-definition]]
 Valid Object ::
     An OpenCL object is considered valid if it meets all of the following
     criteria:
@@ -812,6 +813,10 @@ Valid Object ::
     access the object's backing memory).
 
 An object is only valid in the platform where it was created.
+
+An OpenCL implementation must check for a `NULL` object to determine if an
+object is valid.  The behavior for all other invalid objects is
+implementation-defined.
 --
 
 Work-group ::