Currently we have mjames (icon_name) or unicode (label). Unicode has enough icons (symbol charactrers) but the disadvantage of not being rendered the same on different devices and no colors. A mixture of mjames and unicode is very ugly. Colors might be added to unicode as well (using font-color css style). Unicode has the disadvantage of not being fully supported by all browsers but there's an option for this. Unicode is also being used by workflow states.