anchor.diff:                       :max-vertex-texture-image-units
                        :max-vertex-atomic-counter-buffers
                        :max-vertex-atomic-counters
  +                     :max-vertex-shader-storage-blocks
  +                     ;; 23.70 implementation dependent tessellation
  +                     ;; control shader limits
                        :max-tess-gen-level
                        :max-patch-vertices
                        :max-tess-control-uniform-components
  -                     :max-tess-evaluation-uniform-components
                        :max-tess-control-texture-image-units
  -                     :max-tess-evaluation-texture-image-units
                        :max-tess-control-output-components
                        :max-tess-patch-components
                        :max-tess-control-total-output-components
  +                     :max-tess-control-input-components
  +                     :max-tess-control-uniform-blocks
  +                     :max-tess-control-atomic-counter-buffers
  +                     :max-tess-control-atomic-counters
  +                     :max-tess-control-shader-storage-blocks
  +                     ;; 23.71 implementation dependent tessellation
  +                     ;; shader limits
  +                     :max-tess-evaluation-uniform-components
  +                     :max-tess-evaluation-texture-image-units
                        :max-tess-evaluation-output-components
  -                     :max-tess-control-input-components
                        :max-tess-evaluation-input-components
  -                     :max-tess-control-uniform-blocks
                        :max-tess-evaluation-uniform-blocks
  -                     :max-tess-control-atomic-counter-buffers
                        :max-tess-evaluation-atomic-counter-buffers
  -                     :max-tess-control-atomic-counters
                        :max-tess-evaluation-atomic-counters
  +                     :max-tess-evaluation-shader-storage-blocks
  +                     ;; 23.72 implementation dependent geometry shader
  +                     ;; limits
                        :max-geometry-uniform-components
                        :max-geometry-uniform-blocks
                        :max-geometry-input-components
  
positive.code:     (format t "GL renderer: ~a~%" (get* :renderer))
      (format t "GL extensions: ~a~%" (get* :extensions))
  
      (loop for i in '(:max-clip-planes
                       :max-clip-distances
                       :max-3d-texture-size
                       :max-texture-size
                       :max-array-texture-layers
                       :max-texture-lod-bias
                       :max-cube-map-texture-size
                       :max-renderbuffer-size
                       :max-pixel-map-table
                       :max-name-stack-depth
                       :max-list-nesting
                       :max-eval-order
                       :max-viewport-dims
                       :max-viewports
                       :viewport-subpixel-bits
                       :viewport-bounds-range
                       :max-attrib-stack-depth
                       :max-client-attrib-stack-depth
                       :aliased-point-size-range
                       :point-size-range
                       :point-size-granularity
                       :smooth-point-size-range
                       :smooth-point-size-granularity
                       :aliased-line-width-range
                       :line-width-range
                       :line-width-granularity
                       :smooth-line-width-range
                       :smooth-line-width-granularity
                       :max-elements-indices
                       :max-elements-vertices
                       :compressed-texture-formats
                       :num-compressed-texture-formats
                       :num-program-binary-formats
                       :program-binary-formats
                       :num-shader-binary-formats
                       :shader-binary-formats
                       :shader-compiler
                       :min-map-buffer-alignment
                       :max-texture-buffer-size
                       :max-rectangle-texture-size
                       :num-extensions
                       :context-flags
                       :max-texture-units
                       :max-vertex-attribs
                       :max-vertex-uniform-components
                       :max-vertex-uniform-vectors
  
negative.code:                      :max-vertex-streams
                       :max-geometry-atomic-counter-buffers
                       :max-geometry-atomic-counters
                       :max-geometry-shader-storage-blocks
                       ;; 23.73 implementation dependent fragment shader
                       ;; limits
                       :max-fragment-uniform-components
                       :max-fragment-uniform-vectors
                       :max-fragment-uniform-blocks
                       :max-fragment-input-components
                       :max-texture-image-units
                       :min-program-texture-gather-offset
                       :max-program-texture-gather-offset
                       :max-texture-units ;; compat
                       :max-texture-coords ;; compat
                       :max-fragment-atomic-counter-buffers
                       :max-fragment-atomic-counters
                       :max-fragment-shader-storage-blocks
                       ;; 23.74 implementation dependent compute shader
                       ;; limits
                       :max-compute-work-group-count
                       :max-compute-work-group-size
                       :max-compute-work-group-invocations
                       :max-compute-uniform-blocks
                       :max-compute-texture-image-units
                       :max-compute-atomic-counter-buffers
                       :max-compute-atomic-counters
                       :max-compute-shared-memory-size
                       :max-compute-uniform-components
                       :max-compute-image-uniforms
                       :max-combined-compute-uniform-components
                       :max-compute-shader-storage-blocks
                       ;; 23.75 implementation dependent aggregate
                       ;; limits
                       :min-program-texel-offset
                       :max-program-texel-offset
                       :max-uniform-buffer-bindings
  