Indicators

I prefer not to use the standard markers (type1, type2, long/buy/up, short/sell/down) because they lack scripting flexibility.

You can however set the marker attribute to any single character, and it will map onto an icon from the WingDings character set. Any single digit for example, will give you that number in a circle. I use [marker="["] to produce the yin & yan symbol for an overbought / oversold marker. There are lots of others that are useful. (Note that to get the pair of scissors, for which the character is ", you need to use \ to escape it as follows: [marker="\""].)

If you use a single character for the marker, then you can set the colour in the same way as you would for any other indicator, you can position it above the plot with [align=above], and/or turn off the label with [label=off].

If you would like to use an icon from a font other than WingDings, or one that is not available via one of the single character mappings, then you need to use [linestyle=text] and [font=WingDings], etc to produce the icon, and possibly another text element for the label using a regular font.