anchor.diff:      let _ariaCurrent          = attr "aria-current"
       let _ariaDescribedBy      = attr "aria-describedby"
       let _ariaDetails          = attr "aria-details"
  -    let _ariaDialog           = attr "aria-dialog"
       let _ariaDisabled         = attr "aria-disabled"
       let _ariaDropEffect       = attr "aria-dropeffect"
       let _ariaErrorMessage     = attr "aria-errormessage"
  
positive.code: 
  
  /// Attributes to support WAI-ARIA accessibility guidelines
  // (values for aria- and role attributes obtained from
  //  http://w3c.github.io/html/infrastructure.html#element-attrdef-aria-role)
  module Accessibility =
      
      // Valid role attributes
      let _roleAlert         = attr "role" "alert"
      let _roleAlertDialog   = attr "role" "alertdialog"
      let _roleApplication   = attr "role" "application"
      let _roleArticle       = attr "role" "article"
      let _roleBanner        = attr "role" "banner"
      let _roleButton        = attr "role" "button"
      let _roleCell          = attr "role" "cell"
      let _roleCheckBox      = attr "role" "checkbox"
      let _roleColumnHeader  = attr "role" "columnheader"
      let _roleComboBox      = attr "role" "combobox"
      let _roleComplementary = attr "role" "complementary"
      let _roleContentInfo   = attr "role" "contentinfo"
      let _roleDefinition    = attr "role" "definition"
      let _roleDialog        = attr "role" "dialog"
      let _roleDirectory     = attr "role" "directory"
      let _roleDocument      = attr "role" "document"
      let _roleFeed          = attr "role" "feed"
      let _roleFigure        = attr "role" "figure"
      let _roleForm          = attr "role" "form"
      let _roleGrid          = attr "role" "grid"
      let _roleGridCell      = attr "role" "gridcell"
      let _roleGroup         = attr "role" "group"
      let _roleHeading       = attr "role" "heading"
      let _roleImg           = attr "role" "img"
      let _roleLink          = attr "role" "link"
      let _roleList          = attr "role" "list"
      let _roleListBox       = attr "role" "listbox"
      let _roleListItem      = attr "role" "listitem"
      let _roleLog           = attr "role" "log"
      let _roleMain          = attr "role" "main"
      let _roleMarquee       = attr "role" "marquee"
      let _roleMath          = attr "role" "math"
      let _roleMenubar       = attr "role" "menubar"
      let _roleNavigation    = attr "role" "navigation"
      let _roleNone          = attr "role" "none"
      let _roleNote          = attr "role" "note"
      let _roleOption        = attr "role" "option"
      let _rolePresentation  = attr "role" "presentation"
      let _roleProgressBar   = attr "role" "progressbar"
      let _roleRadio         = attr "role" "radio"
      let _roleRadioGroup    = attr "role" "radiogroup"
      let _roleRegion        = attr "role" "region"
      let _roleRow           = attr "role" "row"
      let _roleRowGroup      = attr "role" "rowgroup"
      let _roleRowHeader     = attr "role" "rowheader"
      let _roleScrollBar     = attr "role" "scrollbar"
      let _roleSearch        = attr "role" "search"
      let _roleSearchBox     = attr "role" "searchbox"
      let _roleSeparator     = attr "role" "separator"
      let _roleSlider        = attr "role" "slider"
      let _roleSpinButton    = attr "role" "spinbutton"
      let _roleStatus        = attr "role" "status"
      let _roleSwitch        = attr "role" "switch"
      let _roleTab           = attr "role" "tab"
      let _roleTable         = attr "role" "table"
      let _roleTabList       = attr "role" "tablist"
      let _roleTabPanel      = attr "role" "tabpanel"
      let _roleTerm          = attr "role" "term"
      let _roleTextBox       = attr "role" "textbox"
      let _roleTimer         = attr "role" "timer"
      let _roleToolBar       = attr "role" "toolbar"
      let _roleToolTip       = attr "role" "tooltip"
      let _roleTree          = attr "role" "tree"
      let _roleTreeGrid      = attr "role" "treegrid"
      let _roleTreeItem      = attr "role" "treeitem"
      
      // Valid aria attributes
      let _ariaActiveDescendant = attr "aria-activedescendant"
      let _ariaAtomic           = attr "aria-atomic"
      let _ariaAutocomplete     = attr "aria-autocomplete"
  
negative.code:     let _ariaLabelledBy       = attr "aria-labeledby"
      let _ariaLevel            = attr "aria-level"
      let _ariaLive             = attr "aria-live"
      let _ariaModal            = attr "aria-modal"
      let _ariaMultiline        = attr "aria-multiline"
      let _ariaMultiSelectable  = attr "aria-multiselectable"
      let _ariaOrientation      = attr "aria-orientation"
  