Coloring image labels in block definitions

i'm pretty sure there is a way to color image labels in block definitions because i looked inside the pause all block before it became a regular block and it used some additional text after (or before) the "$pause" but i forgot what that text was

It's a little too complicated for me to want to type it in here, but look at page 46 of the manual.

It was $pause-1-255-220-0 for pause icon at 1 times normal size with a colour of #ffdc00 or RGB(255, 220, 0)

oh i thought it would be in the "Building a Block" chapter