STANDOUT is not yet supported in FMSLogo.
In other Logo environments, STANDOUT outputs a word that, when printed, appears like the input but displayed in standout mode (boldface, reverse video, or whatever your terminal does for standout). The word contains terminal-specific magic characters at the beginning and end; in between is the printed form (as if displayed using TYPE) of the input. The output is always a word, even if the input is of some other type, but it may include spaces and other formatting characters.
SHOW (LIST "This "is STANDOUT "very "important)This is very important
SHOW STANDOUT [1 2 3][1 2 3]