StandardForm
A standard form for representing math, colors, dates, graphics, which comes with visual decorations
This is a default representation used in output cells. You can apply it to expressions before using in EditorView and InputEditor and CellPrint
Example
Stylize an output form of a symbol
specialSymbol /: MakeBoxes[specialSymbol, StandardForm] := With[{
o = Graphics[Disk[], ImageSize->100, ImagePadding->None]
},
ViewBox[specialSymbol, o]
]
An expression will not be revealed